Apparatus and method for measuring weight of an occupying item of a seat

ABSTRACT

Vehicle seat structure including a seat defining a surface adapted to contact an occupying item and a weight sensor arrangement arranged in connection with the seat for providing an indication of the weight applied by the occupying item to the surface of the seat. The weight sensor arrangement includes conductive members spaced apart from one another such that a capacitance develops between opposed ones of the conductive members upon incorporation of the conductive members in an electrical circuit. The capacitance is based on the space between the conductive members which varies in relation to the weight applied by the occupying item to the surface of the seat.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/849,559 filed May 4, 2001 which is a continuation-in-part of U.S.patent application Ser. No. 09/193,209 filed Nov. 17, 1998, now U.S.Pat. No. 6,242,701, which in turn is a continuation-in-part of U.S.patent application Ser. No. 09/128,490 filed Aug. 4, 1998, now U.S. Pat.No. 6,078,854, which is both a continuation-in-part of U.S. patentapplication Ser. No. 08/474,783 filed Jun. 7, 1995, now U.S. Pat. No.5,822,707, and a continuation-in-part of U.S. patent application Ser.No. 08/970,822 filed Nov. 14, 1997, now U.S. Pat. No. 6,081,757.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for measuring theweight of an occupying item of a seat, in particular, a seat in anautomotive vehicle.

The present invention also relates to apparatus and methods foradjusting a vehicle component, system or subsystem in which theoccupancy of a seat, also referred to as the “seated state” herein, isevaluated using at least a weight measuring apparatus and the component,system or subsystem may then be adjusted based on the evaluatedoccupancy thereof. The vehicle component, system or subsystem,hereinafter referred to simply as a component, may be any adjustablecomponent of the vehicle including, but not limited to, the bottomportion and backrest of the seat, the rear view and side mirrors, thebrake, clutch and accelerator pedals, the steering wheel, the steeringcolumn, a seat armrest, a cup holder, the mounting unit for a cellulartelephone or another communications or computing device and the visors.Further, the component may be a system such an as airbag system, thedeployment or suppression of which is controlled based on theseated-state of the seat. The component may also be an adjustableportion of a system the operation of which might be advantageouslyadjusted based on the seated-state of the seat, such as a device forregulating the inflation or deflation of an airbag that is associatedwith an airbag system.

The present invention also relates to apparatus and method forautomatically adjusting a vehicle component to a selected or optimumposition for an occupant of a seat based on at least two measuredmorphological characteristics of the occupant, one of which is theweight of the occupant. Other morphological characteristics include theheight of the occupant, the length of the occupant's arms, the length ofthe occupant's legs, the occupant's head diameter and the inclination ofthe occupant's back relative to the seat bottom. Other, unlistedmorphological characteristics are also envisioned for use in theinvention.

BACKGROUND OF THE INVENTION

Automobiles equipped with airbags are well known in the prior art. Insuch airbag systems, the car crash is sensed and the airbags rapidlyinflated thereby insuring the safety of an occupation in a car crash.Many lives have now been saved by such airbag systems. However,depending on the seated state of an occupant, there are cases where hisor her life cannot be saved even by present airbag systems. For example,when a passenger is seated on the front passenger seat in a positionother than a forward facing, normal state, e.g., when the passenger isout of position and near the deployment door of the airbag, there willbe cases when the occupant will be seriously injured or even killed bythe deployment of the airbag.

Also, sometimes a child seat is placed on the passenger seat in a rearfacing position and there are cases where a child sitting in such a seathas been seriously injured or killed by the deployment of the airbag.

Furthermore, in the case of a vacant seat, there is no need to deploy anairbag, and in such a case, deploying the airbag is undesirable due to ahigh replacement cost and possible release of toxic gases into thepassenger compartment. Nevertheless, most airbag systems will deploy theairbag in a vehicle crash even if the seat is unoccupied.

For these reasons, there has been proposed a seated-state detecting unitsuch as disclosed in the following U.S. patents, which are incorporatedherein by reference in their entirety to the extent the disclosure ofthese patents is necessary, assigned to the current assignee of thepresent application: Breed et al. U.S. Pat. No. 5,563,462); Breed et al.(U.S. Pat. No. 5,829,782); Breed et al. (U.S. Pat. No. 5,822,707): Breedet al. (U.S. Pat. No. 5,694,320); Breed et al. (U.S. Pat. No.5,748,473); and Varga et al. (U.S. Pat. No. 5,943,295). Typically, insome of these designs three or four sensors or sets of sensors areinstalled at three or four points in a vehicle passenger compartment fortransmitting ultrasonic or electromagnetic waves toward the passenger ordriver's seat and receiving the reflected waves. Using appropriatehardware and software, the approximate configuration of the occupancy ofeither the passenger or driver seat can be determined therebyidentifying and categorizing the occupancy of the relevant seat.

However, in the aforementioned literature using ultrasonics, the patternof reflected ultrasonic waves from an adult occupant who may be out ofposition is sometimes similar to the pattern of reflected waves from arear facing child seat. Also, it is sometimes difficult to discriminatethe wave pattern of a normally seated child with the seat in a rearfacing position from an empty seat with the seat in a more forwardposition. In other cases, the reflected wave pattern from a thinslouching adult with raised knees can be similar to that from a rearfacing child seat. In still other cases, the reflected pattern from apassenger seat which is in a forward position can be similar to thereflected wave pattern from a seat containing a forward facing childseat or a child sitting on the passenger seat. In each of these cases,the prior art ultrasonic systems can suppress the deployment of anairbag when deployment is desired or, alternately, can enable deploymentwhen deployment is not desired.

If the discrimination between these cases can be improved, then thereliability of the seated-state detecting unit can be improved and morepeople saved from death or serious injury. In addition, the unnecessarydeployment of an airbag can be prevented.

With respect to the adjustment of a vehicular seat, the adjustment of anautomobile seat occupied by a driver of the vehicle is now accomplishedby the use of either electrical switches and motors or by mechanicallevers. As a result, the driver's seat is rarely placed at the properdriving position which is defined as the seat location which places theeyes of the driver in the so-called “eye ellipse” and permits him or herto comfortably reach the pedals and steering wheel. The “eye ellipse” isthe optimum eye position relative to the windshield and rear view mirrorof the vehicle.

The eye ellipse, which is actually an ellipsoid, is rarely achieved bythe actions of the driver for a variety of reasons. One specific reasonis the poor design of most seat adjustment systems particularly theso-called “4-way-seat”. It is known that there are three degrees offreedom of a seat bottom, namely vertical, longitudinal, and rotationabout the lateral or pitch axis. The 4-way-seat provides four motions tocontrol the seat: (1) raising or lowering the front of the seat, (2)raising or lowering the back of the seat, (3) raising or lowering theentire seat, (4) moving the seat fore and aft. Such a seat adjustmentsystem causes confusion since there are four control motions for threedegrees of freedom. As a result, vehicle occupants are easily frustratedby such events as when the control to raise the seat is exercised, theseat not only is raised but is also rotated. Occupants thus find itdifficult to place the seat in the optimum location using this systemand frequently give up trying leaving the seat in an improper drivingposition

Many vehicles today are equipped with a lumbar support system that isnever used by most occupants. One reason is that the lumbar supportcannot be preset since the shape of the lumbar for different occupantsdiffers significantly, i.e., a tall person has significantly differentlumbar support requirements than a short person. Without knowledge ofthe size of the occupant, the lumbar support cannot be automaticallyadjusted.

As discussed in the above referenced '320 patent, in approximately 95%of the cases where an occupant suffers a whiplash injury, the headrestis not properly located to protect him or her in a rear impactcollision. Also, the stiffness and damping characteristics of a seat arefixed and no attempt is made in any production vehicle to adjust thestiffness and damping of the seat in relation to either the size orweight of an occupant, or to the environmental conditions such as roadroughness. All of these adjustments, if they are to be doneautomatically, require knowledge of the morphology of the seat occupant.

Systems are now being used to attempt to identify the vehicle occupantbased on a coded key or other object carried by the occupant. Thisrequires special sensors within the vehicle to recognize the codedobject. Also, the system only works if the coded object is used by theparticular person for whom the vehicle was programmed. If the vehicle isused by a son or daughter, for example, who use their mother's key thenthe wrong seat adjustments are made. Also, these systems preserve thechoice of seat position without any regard for the correctness of theseat position. With the problems associated with the 4-way seats, it isunlikely that the occupant ever properly adjusts the seat. Therefore,the error will be repeated every time the occupant uses the vehicle.

Moreover, these coded systems are a crude attempt to identify theoccupant. An improvement can be made if the morphologicalcharacteristics of the occupant can be measured as described below. Suchmeasurements can be made of the height and weight, for example, and usednot only to adjust a vehicular component to a proper position but alsoto remember that position, as fine tuned by the occupant, forre-positioning the component the next time the occupant occupies theseat. For the purposes herein, a morphological characteristic will meanany measurable property of a human such as height, weight, leg or armlength, head diameter etc.

As discussed more fully below, in a preferred implementation, once atleast one and preferably two of the morphological characteristics of adriver are determined, e.g., by measuring his or her height and weight,the component such as the seat can be adjusted and other features orcomponents can be incorporated into the system including, for example,the automatic adjustment of the rear view and/or side mirrors based onseat position and occupant height. In addition, a determination of anout-of-position occupant can be made and based thereon, airbagdeployment suppressed if the occupant is more likely to be injured bythe airbag than by the accident without the protection of the airbag.Furthermore, the characteristics of the airbag including the amount ofgas produced by the inflator and the size of the airbag exit orificescan be adjusted to provide better protection for small lightweightoccupants as well as large, heavy people. Even the direction of theairbag deployment can, in some cases, be controlled.

Still other features or components can now be adjusted based on themeasured occupant morphology as well as the fact that the occupant cannow be identified. Some of these features or components include theadjustment of seat armrest, cup holder, steering wheel (angle andtelescoping), pedals, phone location and for that matter the adjustmentof all things in the vehicle which a person must reach or interact with.Some items that depend on personal preferences can also be automaticallyadjusted including the radio station, temperature, ride and others.

Heretofore, various methods have been proposed for measuring the weightof an occupying item of a vehicular seat. The methods include pads,sheets or films that have placed in the seat cushion which attempt tomeasure the pressure distribution of the occupying item. Prior to itsfirst disclosure in U.S. Pat. No.5,822,707 referenced above, systems formeasuring occupant weight based on the strain in the seat structure hadnot been considered. Prior art weight measurement systems have beennotoriously inaccurate. Thus, a more accurate weight measuring system isdesirable. The strain measurement systems described herein,substantially eliminate the inaccuracy problems of prior art systems andpermit an accurate determination of the weight of the occupying item ofthe vehicle seat. Additionally, as disclosed herein, in many cases,sufficient information can be obtained for the control of a vehiclecomponent without the necessity of determining the entire weight of theoccupant. For example, the force that the occupant exerts on one of thethree support members may be sufficient.

Most, if not all, of the problems discussed above are difficult to solveor unsolvable using conventional technology.

OBJECTS OF THE INVENTION

Accordingly, it is a principal object of the present invention toprovide new and improved apparatus and methods for measuring the weightof an occupying item on a vehicle seat which apparatus and methods maybe integrated into vehicular component adjustment apparatus and methodswhich evaluate the occupancy of the seat and adjust the location and/ororientation relative to the occupant and/or operation of a part of thecomponent or the component in its entirety based on the evaluatedoccupancy of the seat.

It is another object of the present invention to provide new andimproved vehicular seats including a weight measuring feature and weightmeasuring methods for implementation in connection with vehicular seats.

It is yet another object of the present invention to provide new andimproved vehicular seats in which the weight applied by an occupyingitem to the seat is measured based on capacitance between conductiveand/or metallic members underlying the seat cushion.

It is another object of the present invention to provide new andimproved adjustment apparatus and methods that evaluate the occupancy ofthe seat and adjust the location and/or orientation relative to theoccupant and/or operation of a part of the component or the component inits entirety based on the evaluated occupancy of the seat and on ameasurement of the occupant's weight or a measurement of a force exertedby the occupant on the seat.

It is another object of the present invention to provide new andimproved adjustment apparatus and methods that evaluate the occupancy ofthe seat by a combination of ultrasonic sensors and additional sensorsand adjust the location and/or orientation relative to the occupantand/or operation of a part of the component or the component in itsentirety based on the evaluated occupancy of the seat.

It is another object of the present invention to provide new andimproved adjustment apparatus and methods that reliably discriminatebetween a normally seated passenger and a forward facing child seat,between an abnormally seated passenger and a rear facing child seat, andwhether or not the seat is empty and adjust the location and/ororientation relative to the occupant and/or operation of a part of thecomponent or the component in its entirety based thereon.

It is another object of the present invention to provide an improvedweight measurement system and thereby improve the accuracy of anotherapparatus or system which utilizes measured weight as input, e.g., acomponent adjustment apparatus.

It is another object of the present invention to provide new andimproved adjustment apparatus and methods that evaluate the occupancy ofthe seat without the problems mentioned above.

Additional objects and advantages of this invention include:

1. To provide a system for passively and automatically adjusting theposition of a vehicle component to a near optimum location based on thesize of an occupant.

2. To provide a system for recognizing a particular occupant of avehicle and thereafter adjusting various components of the vehicle inaccordance with the preferences of the recognized occupant.

3. To provide systems for approximately locating the eyes of a vehicledriver to thereby permit the placement of the driver's eyes at aparticular location in the vehicle.

4. To provide a pattern recognition system to permit more accuratelocation of an occupant's head and the parts thereof and to use thisinformation to adjust a vehicle component.

5. To provide a method of determining whether a seat is occupied and, ifnot, leaving the seat at a neutral position.

6. To provide a system for automatically adjusting the position ofvarious components of the vehicle to permit safer and more effectiveoperation of the vehicle including the location of the pedals andsteering wheel.

7. To determine whether an occupant is out-of-position relative to theairbag and if so, to suppress deployment of the airbag in a situation inwhich the airbag would otherwise be deployed.

8. To adjust the flow of gas into and/or out of the airbag based on themorphology and position of the occupant to improve the performance ofthe airbag in reducing occupant injury.

9. To provide a system where the morphological characteristics of anoccupant are measured by sensors located within the seat.

10. To provide a system and method wherein the weight of an occupant isdetermined utilizing sensors located on the seat structure.

Further objects of the present invention will become apparent from thefollowing discussion of the preferred embodiments of the invention.

SUMMARY OF THE INVENTION

Accordingly, in order to achieve one or more of the objects above, avehicle seat structure comprises a seat defining a surface adapted tocontact an occupying item and a weight sensor arrangement arranged inconnection with the seat for providing an indication of the weightapplied by the occupying item to the surface of the seat. The weightsensor arrangement includes conductive members spaced apart from oneanother such that a capacitance develops between opposed ones of theconductive members upon incorporation of the conductive members in anelectrical circuit. The capacitance is based on the space between theconductive members which varies in relation to the weight applied by theoccupying item to the surface of the seat. The weight sensor arrangementmay include a pair of non-metallic substrates and a layer of materialsituated between the non-metallic substrates, possibly a compressiblematerial. The conductive members may comprise a first electrode arrangedon a first side of the material layer and a second electrode arranged ona second side of the material layer. The weight sensor arrangement maybe arranged in connection with slide mechanisms adapted to support theseat on a substrate of the vehicle while enabling movement of the seat,possibly between the slide mechanisms and the seat. If bolts attach theseat to the slide mechanisms, the conductive members may be annular andplaced on the bolts.

Another embodiment of a seat structure comprises a seat defining asurface adapted to contact an occupying item, slide mechanisms adaptedto support the seat on a substrate of the vehicle while enablingmovement of the seat and a weight sensor arrangement interposed betweenthe seat and the slide mechanisms for measuring displacement of the seatwhich provides an indication of the weight applied by the occupying itemto the seat. The weight sensor arrangement can include a capacitancesensor which measures a capacitance which varies in relation to thedisplacement of the seat. The capacitance sensor can include conductivemembers spaced apart from one another such that a capacitance developsbetween opposed ones of the conductive members upon incorporation of themembers in an electrical circuit, the capacitance being based on thespace between the members which varies in relation to the weight appliedby the occupying item to the seat.

The weight sensor arrangement can comprise a spring system arrangedunderneath a seat cushion and a sensor arranged in association with thespring system for generating a signal based on downward movement of thecushion caused by occupancy of the seat which is indicative of theweight of the occupying item. The sensor may be a displacement sensorstructured and arranged to measure displacement of the spring systemcaused by occupancy of the seat. Such a sensor can comprise a springretained at both ends and which is tensioned upon downward movement ofthe spring system and measuring means for measuring a force in thespring indicative of weight of the occupying item. The measuring meanscan comprise a strain gage for measuring strain of the spring or aforce-measuring device.

The sensor may also comprise a support, a cable retained at one end bythe support and a length-measuring device arranged at an opposite end ofthe cable for measuring elongation of the cable indicative of weight ofthe occupying item. The sensor can also comprises one or more SAW straingages and/or structured and arranged to measure a physical state of thespring system.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the inventionand are not meant to limit the scope of the invention as encompassed bythe claims.

FIG. 1 shows a seated-state detecting unit in accordance with thepresent invention and the connections between ultrasonic orelectromagnetic sensors, a weight sensor, a reclining angle detectingsensor, a seat track position detecting sensor, a heartbeat sensor, amotion sensor, a neural network circuit, and an airbag system installedwithin a vehicle compartment;

FIG. 2 is a perspective view of a vehicle showing the position of theultrasonic or electromagnetic sensors relative to the driver and frontpassenger seats.;

FIG. 3 is a circuit diagram of the seated-state detecting unit of thepresent invention;

FIGS. 4(a), 4(b) and 4(c) are each a diagram showing the configurationof the reflected waves of an ultrasonic wave transmitted from eachtransmitter of the ultrasonic sensors toward the passenger seat,obtained within the time that the reflected wave arrives at a receiver,FIG. 4(a) showing an example of the reflected waves obtained when apassenger is in a normal seated-state, FIG. 4(b) showing an example ofthe reflected waves obtained when a passenger is in an abnormalseated-state (where the passenger is seated too close to the instrumentpanel), and FIG. 4(c) showing a transmit pulse;

FIG. 5 is a diagram of the data processing of the reflected waves fromthe ultrasonic or electromagnetic sensors;

FIG. 6 is a flowchart showing the training steps of a neural networkcircuit;

FIG. 7(a) is an explanatory diagram of a process for normalizing thereflected wave and shows normalized reflected waves; and

FIG. 7(b) is a diagram similar to FIG. 7(a) showing a step of extractingdata based on the normalized reflected waves and a step of weighting theextracted data by employing the data of the seat track positiondetecting sensor, the data of the reclining angle detecting sensor, andthe data of the weight sensor.

FIG. 8 is a perspective view of an automatic seat adjustment system,with the seat shown in phantom, with a movable headrest and sensors formeasuring the height of the occupant from the vehicle seat showingmotors for moving the seat and a control circuit connected to thesensors and motors.

FIG. 9 is a perspective view of the seat shown in FIG. 8 with theaddition of a weight sensor shown mounted onto the seat.

FIG. 9A is a view taken along line 9A—9A in FIG. 9.

FIG. 9B is an enlarged view of the section designated 9B in FIG. 9A.

FIG. 9C is a view of another embodiment of a seat with a weight sensorsimilar to the view shown in FIG. 9A.

FIG. 9D is a view of another embodiment of a seat with a weight sensorin which a SAW strain gage is placed on the bottom surface of thecushion.

FIG. 10 is a side plan view of the interior of an automobile, withportions cut away and removed, with two occupant height measuringsensors, one mounted into the headliner above the occupant's head andthe other mounted onto the A-pillar and also showing a seatbeltassociated with the seat wherein the seatbelt has an adjustable upperanchorage point which is automatically adjusted based on the height ofthe occupant.

FIG. 11 is a view of the seat of FIG. 8 showing motors for changing thetilt of seat back and the lumbar support.

FIG. 12 is a view of the seat of FIG. 8 showing a system for changingthe stiffness and the damping of the seat.

FIG. 13 is a view as in FIG. 10 showing a driver and driver seat with anautomatically adjustable steering column and pedal system which isadjusted based on the morphology of the driver.

FIG. 14 is a perspective view of the interior of the passengercompartment of an automobile, with parts cut away and removed, showing avariety of transmitters that can be used in a phased array system.

FIG. 15 is a view similar to FIG. 8 showing the occupant's eyes and theseat adjusted to place the eyes at a particular vertical position forproper viewing through the windshield and rear view mirror.

FIG. 16 is a view similar to FIG. 8 showing an inflated airbag and anarrangement for controlling both the flow of gas into and the flow ofgas out of the airbag during the crash where the determination is madebased on a height sensor located in the headrest and a weight sensor inthe seat.

FIG. 17A is a schematic drawing of the basic embodiment of theadjustment system in accordance with the invention.

FIG. 17B is a schematic drawing of another basic embodiment of theadjustment system in accordance with the invention.

FIG. 18 is a perspective view of a one embodiment of an apparatus formeasuring the weight of an occupying item of a seat illustrating weightsensing transducers mounted on a seat control mechanism portion which isattached directly to the seat.

FIG. 19 illustrates a seat structure with the seat cushion and backcushion removed illustrating a three-slide attachment of the seat to thevehicle and preferred mounting locations on the seat structure forstrain measuring weight sensors of an apparatus for measuring the weightof an occupying item of a seat in accordance with the invention.

FIG. 19A illustrates an alternate view of the seat structure transducermounting location taken in the circle A of FIG. 19 FIG. with theaddition of a gusset and where the strain gage is mounted onto thegusset.

FIG. 19B illustrates a mounting location for a weight sensing transduceron a centralized transverse support member in an apparatus for measuringthe weight of an occupying item of a seat in accordance with theinvention.

FIGS. 20A-20C illustrate three alternate methods of mounting straintransducers of an apparatus for measuring the weight of an occupyingitem of a seat in accordance with the invention onto a tubular seatsupport structural member.

FIG. 21 illustrates an alternate weight sensing transducer utilizingpressure sensitive transducers.

FIG. 21A illustrates a part of another alternate weight sensing systemfor a seat.

FIG. 22 illustrates an alternate seat structure assembly utilizingstrain transducers.

FIG. 22A is a perspective view of a cantilevered beam type load cell foruse with the weight measurement system of this invention for mountinglocations of FIG. 22, for example.

FIG. 22B is a perspective view of a simply supported beam type load cellfor use with the weight measurement system of this invention as analternate to the cantilevered load cell of FIG. 22A.

FIG. 22C is an enlarged view of the portion designated 22C in FIG. 22B.

FIG. 22D is a perspective view of a tubular load cell for use with theweight measurement system of this invention as an alternate to thecantilevered load cell of FIG. 22A.

FIG. 22E is a perspective view of a torsional beam load cell for usewith the weight measurement apparatus in accordance with the inventionas an alternate to the cantilevered load cell of FIG. 22A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings wherein like reference numbersdesignate the same or similar elements, FIG. 1 shows a passenger seat 1to which an adjustment apparatus including a seated-state detecting unitaccording to the present invention may be applied. The seat 1 includes ahorizontally situated bottom seat portion 2 and a vertically orientedback portion 3. The seat portion 2 is provided with one or more weightsensors 6 and 7 that determine the weight of the object occupying theseat. The coupled portion between the seated portion 2 and the backportion 3 is provided with a reclining angle detecting sensor 9, whichdetects the tilted angle of the back portion 3 relative to the seatportion 2. The seat portion 2 is provided with a seat trackposition-detecting sensor 10. The seat track position detecting sensor10 fulfills a role of detecting the quantity of movement of the seat 1which is moved from a back reference position, indicated by the dottedchain line. Embedded within the seatback is a heartbeat sensor 31 and amotion sensor 33. Attached to the headliner is a capacitance sensor 32.The seat 1 may be the driver seat, the front passenger seat or any otherseat in a motor vehicle as well as other seats in transportationvehicles or seats in non-transportation applications.

Weight measuring means such as the sensors 6 and 7 are associated withthe seat, e.g., mounted into or below the seat portion 2 or on the seatstructure, for measuring the weight applied onto the seat. The weightmay be zero if no occupying item is present. Sensors 6 and 7 mayrepresent a plurality of different sensors which measure the weightapplied onto the seat at different portions thereof or for redundancypurposes, e.g., such as by means of an airbag 7 in the seat portion 2.Such sensors may be in the form of strain, force or pressure sensorswhich measure the force or pressure on the seat or seat back,displacement measuring sensors which measure the displacement of theseat surface or the entire seat such as through the use of strain gagesmounted on the seat structural members, such as 7, or other appropriatelocations, or systems which convert displacement into a pressure whereina pressure sensor can be used as a measure of weight.

As shown in FIG. 2, there are provided four sets of wave-receivingsensor systems 11-14 mounted within the passenger compartment. Each setof sensor systems 11-14 comprises a transmitter and a receiver, whichmay be integrated into a single unit or individual components separatedfrom one another. In this embodiment, the sensor system 11 is mounted onthe upper portion of the front pillar, A-Pillar, of the vehicle. Thesensor system 12 is mounted on the upper portion of the intermediatepillar, B-Pillar. The sensor system 13 is mounted on the roof ceilingportion or the headliner (FIG. 2). The sensor system 14 is mounted nearthe middle of an instrument panel 17 in front of the driver's seat 16(FIG. 2). The sensor systems are preferably ultrasonic orelectromagnetic. Although sensor systems 11-14 are described as beingultrasonic or electromagnetic sensors, the invention is equallyapplicable for other types of sensors (other than ultrasonic orelectromagnetic) which will detect the presence of an occupant from adistance including capacitive sensors. Also, if the sensor systems 11-14are passive infrared sensors, then they may only comprise awave-receiver.

The ultrasonic or electromagnetic sensor systems 11-14 are controlled ordriven, one at a time or simultaneously, by an appropriate drivercircuit such as ultrasonic or electromagnetic sensor driver circuit 18shown in FIG. 3. The transmitters of the ultrasonic or electromagneticsensor systems 11-14 transmit respective ultrasonic or electromagneticwaves toward the seat 1 and transmit pulses (see FIG. 4(c)) in sequenceat times t1, t2, t3 and t4 (t4>t3>t2>t1) or simultaneously (t1=t2=t3=t4)electromagnetic waves are received by the receivers ChA-ChD of theultrasonic or electromagnetic sensors 11-14.

The receiver ChA is associated with the ultrasonic or electromagneticsensor system 13, the receiver ChB is associated with the ultrasonic orelectromagnetic sensor system 14, the receiver ChD is associated withthe ultrasonic or electromagnetic sensor system 11, and the receiver ChDis associated with the ultrasonic or electromagnetic sensor system 12.

The following discussion will apply to the case where ultrasonic sensorsare used although a similar discussion can be presented relative to theuse of electromagnetic sensors such as active infrared sensors, takinginto account the differences in the technologies. Also, the followingdiscussion will relate to an embodiment wherein the seat 1 is the frontpassenger seat. FIGS. 4(a) and 4(b) show examples of the reflectedultrasonic waves USRW that are received by receivers ChA-ChD. FIG. 4(a)shows an example of the reflected wave USRW that is obtained when anadult sits in a normally seated space on the passenger seat 1, whileFIG. 4(b) shows an example of the reflected wave USRW that are obtainedwhen an adult sits in a slouching state (one of the abnormalseated-states) in the passenger seat 1.

In the case of a normally seated passenger, as shown in FIG. 2, thelocation of the ultrasonic sensor system 12 is closest to the passengerA. Therefore, the reflected wave pulse P1 is received earliest aftertransmission by the receiver ChD as shown in FIG. 4(a), and the width ofthe reflected wave pulse P1 is larger. Next, the distance from theultrasonic sensor 13 is closer to the passenger A, so a reflected wavepulse P2 is received earlier by the receiver ChA compared with theremaining reflected wave pulses P3 and P4 . Since the reflected wavepauses P3 and P4 take more time than the reflected wave pulses P1 and P2to arrive at the receivers ChC and ChB, the reflected wave pulses P3 andP4 are received as the timings shown in FIG. 4(a). More specifically,since it is believed that the distance from the ultrasonic sensor system11 to the passenger A is slightly shorter than the distance from theultrasonic sensor system 14 to the passenger A, the reflected wave pulseP3 is received slightly earlier by the receiver ChC than the reflectedwave pulse P4 is received by the receiver ChB.

In the case where the passenger A is sitting in a slouching state in thepassenger seat 1, the distance between the ultrasonic sensor system 11and the passenger A is shortest. Therefore, the time from transmissionat time t3 to reception is shortest, and the reflected wave pulse P3 isreceived by the receiver ChC, as shown in FIG. 4(b). Next, the distancesbetween the ultrasonic sensor system 14 and the passenger A becomesshorter, so the reflected wave pulse P4 is received earlier by thereceiver ChB than the remaining reflected wave pulses P2 and P1. Whenthe distance from the ultrasonic sensor system 13 to the passenger A iscompared with that from the ultrasonic sensor system 12 to the passengerA, the distance from the ultrasonic sensor system 13 to the passenger Abecomes shorter, so the reflected wave pulse P2 is received by thereceiver ChA first and the reflected wave pulse P1 is thus received lastby the receiver ChD.

The configurations of the reflected wave pulses P1-P4, the times thatthe reflected wave pulses P1-P4 are received, the sizes of the reflectedwave pulses P1-P4 are varied depending upon the configuration andposition of an object such as a passenger situated on the frontpassenger seat 1. FIGS. 4(a) and (b) merely show examples for thepurpose of description and therefore it is a matter of course that thepresent invention is not limited to these examples.

The outputs of the receivers ChA-ChD, as shown in FIG. 3, are input to aband pass filter 20 through a multiplex circuit 19 which is switched insynchronization with a timing signal from the ultrasonic sensor drivecircuit 18. The band pass filter 20 removes a low frequency wavecomponent from the output signal based on each of the reflected waveUSRW and also removes some of the noise. The output signal based on eachof the reflected wave USRW is passed through the band pass filter 20,then is amplified by an amplifier 21. The amplifier also removes thehigh frequency carrier wave component in each of the reflected USRW andgenerates an envelope wave signal. This envelope wave signal is input toan analog/digital converter (ADC) 22 and digitized as measured data. Themeasured data is input to a processing circuit 23, which is controlledby the timing signal which is in turn output from the ultrasonic sensordrive circuit 18.

The processing circuit 23 collects measured data at intervals of 7 ms,and 47 data points are generated for each of the ultrasonic sensorsystems 11-14. For each of these reflected waves USRW, the initialreflected wave portion T1 and the last reflected wave portion T2 are cutoff. The reason for this will be described when the training procedureof a neural network circuit is described later, and the description isomitted for now. With this, 32 data points, 31 data points, 37 datapoints, and 38 data points will be sampled by the ultrasonic sensorsystems 11, 12, 13 and 14, respectively. The reason why the number ofdata points differs for each of the ultrasonic sensor systems 11-14 isthat the distance from the passenger seat 1 to the ultrasonic sensorsystems 11-14 differ from one another.

Each of the measured data is input to a normalization circuit 24 andnormalized. The normalized measured data is input to the neural networkcircuit 25 as wave data.

The output of the weight sensor(s) 6 and 7 is amplified by an amplifier26 coupled to the weight sensor(s) 6 and 7 and the amplified output isinput to the analog/digital converter 27.

The reclining angle detecting sensor 9 and the seat trackposition-detecting sensor 10, which each may comprise a variableresistor, are connected to constant-current circuits, respectively. Aconstant-current is supplied from the constant-current circuit to thereclining angle detecting sensor 9, and the reclining angle detectingsensor 9 converts a change in the resistance value on the tilt of theback portion 3 to a specific voltage. This output voltage is input to ananalog/digital converter 28 as angle data, i.e., representative of theangle between the back portion 3 and the seat portion 2. Similarly, aconstant current is supplied from the constant-current circuit to theseat track position-detecting sensor 10 and the seat track positiondetecting sensor 10 converts a change in the resistance value based onthe track position of the seat portion 2 to a specific voltage. Thisoutput voltage is input to an analog/digital converter 29 as seat trackdata. Thus, the outputs of the reclining angle-detecting sensor 9 andthe seat track position-detecting sensor 10 are input to theanalog/digital converters 28 and 29, respectively. Each digital datavalue from the ADCs 28,29 is input to the neural network circuit 25.Although the digitized data of the weight sensor(s) 6 and 7 is input tothe neural network circuit 25, the output of the amplifier 26 is alsoinput to a comparison circuit. The comparison circuit, which isincorporated in the gate circuit algorithm, determines whether or notthe weight of an object on the passenger seat 1 is more than apredetermined weight, such as 60 lbs., for example. When the weight ismore than 60 lbs., the comparison circuit outputs a logic 1 to the gatecircuit to be described later. When the weight of the object is lessthan 60 lbs., a logic 0 is output to the gate circuit.

A heartbeat sensor 31 is arranged to detect a heart beat, and themagnitude thereof, of a human occupant of the seat, if such a humanoccupant is present. The output of the heart beat sensor 31 is input tothe neural network circuit 25. The heartbeat sensor 31 may be of thetype as disclosed in McEwan (U.S. Pat. Nos. 5,573,012 and 5,766,208which are included herein in their entirety by reference). The heartbeatsensor 31 can be positioned at any convenient position relative the seat1 where occupancy is being monitored. A preferred location is within thevehicle seatback.

A capacitive sensor 32 is arranged to detect the presence of anoccupying item on the seat 1 and the output thereof is input to theneural network circuit 25. Capacitor sensors appropriate for thisfunction are disclosed in Kithil (U.S. Pat. No. 5,602,734 which isincorporated herein by reference). Capacitive sensors can in general bemounted at locations 11-14 in FIG. 2 or as shown in FIG. 1.

A motion sensor 33 is arranged to detect motion of an occupying item onthe seat 1 and the output thereof is input to the neural network circuit25. Motion sensors can utilize a micro-power impulse radar (MIR) systemas disclosed, for example, in McEwan (U.S. Pat. No. 5,361,070, which isincluded herein by reference), as well as many other patents by the sameinventor. Motion sensing is accomplished by monitoring a particularrange from the sensor as disclosed in that patent. MIR is one form ofradar which has applicability to occupant sensing and can be mounted atlocations such as 11-14 in FIG. 2. It has an advantage over ultrasonicsensors in that data can be acquired at a higher speed and thus themotion of an occupant can be more easily tracked. The ability to obtainreturns over the entire occupancy range is somewhat more difficult thanwith ultrasound resulting in a more expensive system overall. MIR hasadditional advantages in lack of sensitivity to temperature variationand has a comparable resolution to about 40 kHz ultrasound. Resolutioncomparable to higher frequency is feasible but has not beendemonstrated. Additionally, multiple MIR sensors can be used when highspeed tracking of the motion of an occupant during a crash is requiredsince they can be individually pulsed without interfering with eachthrough time division multiplexing.

The neural network circuit 25 recognizes the seated-state of a passengerA by training as described in several books on Neural Networksreferenced in the above referenced patents and patent applications.Then, after training the seated-state of the passenger A and developingthe neural network weights, the system is tested. The training procedureand the test procedure of the neural network circuit 25 will hereafterbe described with a flowchart shown in FIG. 6.

As diagrammed in FIG. 6, the first step is to mount the four sets ofultrasonic sensor systems 11-14, the weight sensors 6 and 7, thereclining angle detecting sensor 9, and the seat track positiondetecting sensor 10 into a vehicle (step S1). Next, in order to providedata for the neural network circuit 25 to learn the patterns of seatedstates, data is recorded for patterns of all possible seated states anda list is maintained recording the seated states for which data wasacquired. The data from the sensors/transducers 6, 7, 9-14 and 31-33,for a particular occupancy of the passenger seat is called a vector(step S2). It should be pointed out that the use of the reclining angledetecting sensor 9, seat track position detecting sensor 10, heart beatsensor 31, capacitive sensor 32 and motion sensor 33 are not essentialto the detecting apparatus and method in accordance with the invention.However, each of these sensors, in combination with any one or more ofthe other sensors enhances the evaluation of the seated-state of theseat.

For the vectors of data, adults and children each with differentpostures, states of windows etc. within the passenger compartment, andoccupied and unoccupied child seats were selected. The selected adultsinclude people with a variety of different physiques such as fat, lean,small, large, tall, short, and glasses wearing persons. The selectedchildren ranged from an infant to a large child (for example, about 14year old). In addition, the selected postures include, for example, asitting state with legs crossed on a seat, a sitting state with legs onan instrument panel, a sitting state while reading a newspaper, a book,or a map, a sitting state while holding a cup of coffee, a cellulartelephone or a dictation machine, and a slouching state with and withoutraised knees. Furthermore, the selected compartment states includevariations in the seat track position, the window-opening amount,headrest position, and varying positions of a sun-visor. Moreover, amultitude of different models of child seats are used in the forwardfacing position and, where appropriate, in a rear facing position. Therange of weights and the corresponding normalized values are as follows:

Normalized Class Weight Range Value Empty Seat 0 to 2.2 lbs. 0 to 0.01Rear Facing Child Seat 2.2 to 60 lbs. 0.01 to 0.27 Forward Facing ChildSeat 2.2 to 60 lbs. 0.01 to 0.27 Normal Position Adult 60 lbs andgreater 0.27 to 1

Obviously, other weight ranges may also be used in accordance with theinvention and each weight range may be tailored to specific conditions,such as different vehicles. The output of the weight sensors may notcorrespond directly to be weight ranges in the above table. If forexample strain measuring sensors are placed on each of the vehicle seatsupports, such sensors will also respond to the weight of the seatitself. That weight must therefore the remove so that only theadditional weight of an occupying item is measured. Similarly it may bedesirable to place strain-sensing devices on only some of the vehicleseat support structures. In such cases the weight of the occupying itemcan be in inferred from the output of the strain sensing sensors. Thiswill be described in greater detail below.

Various vehicle setups were prepared by a combination of thesevariations and, for in this embodiment, almost 500,000 or more vectorsshould be prepared for the patterns to be used as data for the neuralnetwork training.

Next, based on the training data from the reflected waves of theultrasonic sensor systems 11-14 and the other sensors 6, 7, 31-33, thevector data is collected (step S3). Next, the reflected waves P1-P4 aremodified by removing the initial reflected waves with a short reflectiontime from an object (range gating) (period T1 in FIG. 5) and the lastportion of the reflected waves with a long reflection time from anobject (period P2 in FIG. 5) (step S4). It is believed that thereflected waves with a short reflection time from an object is a due tocross-talk, that is, waves from the transmitters which leaks into eachof their associated receivers ChA-ChD. It is also believed that thereflected waves with a long reflection time are reflected waves from anobject far away from the passenger seat or from multipath reflections.If these two reflected wave portions are used as data, they will addnoise to the training process. Therefore, these reflected wave portionsare eliminated from the data.

As shown in FIG. 7(a), measured data is normalized by making the peaksof the reflected wave pulses P1-P4 equal (step S5). This eliminates theeffects of different reflectivities of different objects and peopledepending on the characteristics of their surfaces such as theirclothing Data from the weight sensor, seat track position sensor andseat reclining angle sensor are also frequently normalized basedtypically on fixed normalization parameters.

Therefore, the normalized data from the ultrasonic transducers the seattrack position detecting sensor 10, the reclining angle detecting sensor9, from the weight sensor(s) 6 and 7, from the heart beat sensor 31, thecapacitive sensor 32 and the motion sensor 33 are input to the neuralnetwork circuit 25, and the neural network circuit 25 is then trained onthis data. More specifically, the neural network circuit 25 adds up thenormalized data from the ultrasonic transducers, from the seat trackposition detecting sensor 10, from the reclining angle detecting sensor9, from the weight sensor(s) 6 and 7, from the heart beat sensor 31,from the capacitive sensor 32 and from the motion sensor 33 with eachdata point multiplied by a associated weight according to theconventional neural network process to determine correlation function(step S 6).

In this embodiment, 144 data points are appropriately interconnected at25 connecting points of layer 1, and each data point is mutuallycorrelated through the neural network training and weight determinationprocess. The 144 data points consist of 138 measured data points fromthe ultrasonic transducers, the data (139th) from the seat trackposition detecting sensor 10, the data (140th) from the reclining angledetecting sensor 9, the data (141st) from the weight sensor(s) 6, thedata (142^(nd)) from the heart beat sensor 31, the data (143^(rd)) fromthe capacitive sensor and the data (144^(th)) from the motion sensor.Each of the connecting points of the layer 1 has an appropriatethreshold value, and if the sum of measured data exceeds the thresholdvalue, each of the connecting points will output a signal to theconnecting points of layer 2. Although the weight sensor input is shownas a single input, in general there will be a separate input from eachweight sensor used. For example, if we the seat has four seat supportsand if a strained measuring element is used on each support, what willbe four data inputs to neural network.

The connecting points of the layer 2 comprises 20 points, and the 25connecting points of the layer 1 are appropriately interconnected as theconnecting points of the layer 2. Similarly, each data is mutuallycorrelated through the training process and weight determination asdescribed above and in the above referenced neural network texts. Eachof the 20 connecting points of the layer 2 has an appropriate thresholdvalue, and if the sum of measured data exceeds the threshold value, eachof the connecting points will output a signal to the connecting pointsof layer 3.

The connecting points of the layer 3 comprises 3 points, and theconnecting points of the layer 2 are interconnected at the connectingpoints of the layer 3 so that each data is mutually correlated asdescribed above. If the sum of the outputs of the connecting points oflayer 2 exceeds a threshold value, the connecting points of the latter 3will output Logic values (100), (010), and (001) respectively, forexample.

The threshold value of each connecting point is determined bymultiplying weight coefficients and summing up the results in sequence,and the aforementioned training process is to determine a weightcoefficient Wj so that the threshold value (ai) is a previouslydetermined output.

ai=ΣWj·Xj(j=1to N)

wherein Wj is the weight coefficient,

Xj is the data and

N is the number of samples.

Based on this result of the training, the neural network circuit 25generates the weights for the coefficients of the correlation functionor the algorithm (step S 7).

At the time the neural network circuit 25 has learned a suitable numberof patterns of the training data, the result of the training is testedby the test data. In the case where the rate of correct answers of theseated-state detecting unit based on this test data is unsatisfactory,the neural network circuit is further trained and the test is repeated.In this embodiment, the test was performed based on about 600,000 testpatterns. When the rate of correct test result answers was at about 98%,the training was ended.

The neural network circuit 25 has outputs 25 a, 25 b and 25 c. Each ofthe outputs 25 a, 25 b and 25 c outputs a signal of logic 0 or 1 to agate circuit or algorithm 30. Based on the signals from the outputs 25a, 25 b and 25 c, any one of these combination (100), (010) and (001) isobtained. In another preferred embodiment, all data for the empty seatwas removed from the training set and the empty seat case was determinedbased on the output of the weight sensor alone. This simplifies theneural network and improves its accuracy.

In this embodiment, the output (001) correspond to a vacant seat, a seatoccupied by an inanimate object or a seat occupied by a pet (VACANT),the output (010) corresponds to a rear facing child seat (RFCS) or anabnormally seated passenger (ASP), and the output (100) corresponds to anormally seated passenger (NSP) or a forward facing child seat (FFCS).

The gate circuit (seated-state evaluation circuit) 30 can be implementedby an electronic circuit or by a computer algorithm by those skilled inthe art and the details will not be presented here. The function of thegate circuit 30 is to remove the ambiguity that sometimes results whenultrasonic sensors and seat position sensors alone are used. Thisambiguity is that it is sometimes difficult to differentiate between arear facing child seat (RFCS) and an abnormally seated passenger (ASP),or between a normally seated passenger (NSP) and a forward facing childseat (FFCS). By the addition of one or more weight sensors in thefunction of acting as a switch when the weight is above or below 60lbs., it has been found that this ambiguity can be eliminated. The gatecircuit therefore takes into account the output of the neural networkand also the weight from the weight sensor(s) as being above or below 60lbs. and thereby separates the two cases just described and results infive discrete outputs.

Thus, the gate circuit 30 fulfills a role of outputting five kinds ofseated-state evaluation signals, based on a combination of three kindsof evaluation signals from the neural network 25 and superimposedinformation from the weight sensor(s). The five seated-state evaluationsignals are input to an airbag deployment determining circuit that ispart of the airbag system and will not be described here. Naturally, asdisclosed in the above reference patents and patent applications, theoutput of this system can also be used to activate a variety of lightsor alarms to indicate to the operator of the vehicle the seated state ofthe passenger. Naturally, the system that has been here described forthe passenger side is also applicable for the most part for the driverside.

In this embodiment, although the neural network circuit 25 has beenemployed as an evaluation circuit, the mapping data of the coefficientsof a correlation function may also be implemented or transferred to amicrocomputer to constitute the valuation circuit (see Step S 8 in FIG.6).

According to the seated-state detecting unit of the present invention,the identification of a vacant seat (VACANT), a rear facing child seat(RFCS), a forward facing child seat (FFCS), a normally seated adultpassenger (NSP), an abnormally seated adult passenger (ASP), can bereliably performed. Based on this identification, it is possible tocontrol a component, system or subsystem in the vehicle. For example, aregulation valve which controls the inflation or deflation of an airbagmay be controlled based on the evaluated identification of the occupantof the seat. This regulation valve may be of the digital or analog type.A digital regulation valve is one that is in either of two states, openor closed. The control of the flow is then accomplished by varying thetime that the valve is open and closed, i.e., the duty cycle.

Moreover, the seated-state detecting unit described above may be used ina component adjustment system and method described below when thepresence of a human being occupying the seat is detected.

The component adjustment system and methods in accordance with theinvention automatically and passively adjust the component based on themorphology of the occupant of the seat. As noted above, the adjustmentsystem may include the seated-state detecting unit described above sothat it will be activated if the seated-state detecting unit detectsthat an adult or child occupant is seated on the seat, i.e., theadjustment system will not operate if the seat is occupied by a childseat, pet or inanimate objects. Obviously, the same system can be usedfor any seat in the vehicle including the driver seat and the passengerseat(s). This adjustment system may incorporated the same components asthe seated-state detecting unit described above, i.e., the samecomponents may constitute a part of both the seated-state detecting unitand the adjustment system, e.g., the weight measuring means.

The adjustment system described herein, although improved over the priorart, will at best be approximate since two people, even if they areidentical in all other respects, may have a different preferred drivingposition or other preferred adjusted component location or orientation.A system that automatically adjusts the component, therefore, must learnfrom its errors. Thus, when a new occupant sits in the vehicle, forexample, the system automatically estimates the best location of thecomponent for that occupant and moves the component to that location,assuming it is not already at the best location. If the occupant changesthe location, the system must remember that change and incorporate itinto the adjustment the next time that person enters the vehicle and isseated in the same seat. Therefore, the system need not make a perfectselection the first time but it must remember the person and theposition the component was in for that person. The system, therefore,makes one, two or three measurements of morphological characteristics ofthe occupant and then adjusts the component based on an algorithm. Theoccupant will correct the adjustment and the next time that the systemmeasures the same measurements for those measurement characteristics, itwill set the component to the corrected position. As such, preferredcomponents for which the system in accordance with the invention is mostuseful are those which affect a driver of the vehicle and relate to thesensory abilities of the driver, i.e., the mirrors, the seat, thesteering wheel and steering column and accelerator, clutch and brakepedals.

The first characteristic used is a measurement of the height of theoccupant from the vehicle seat. This can be done by a sensor in theceiling of the vehicle but this becomes difficult since, even for thesame seat location, the head of the occupant will not be at the sameangle with respect to the seat and therefore the angle to aceiling-mounted sensor is in general unknown at least as long as onlyone ceiling mounted sensor is used. This problem can be solved if two orthree sensors are used as described in more detail below. The simplestimplementation is to place the sensor in the seat. In the '320 patentmentioned above, a rear impact occupant protection apparatus isdisclosed which uses sensors mounted within the headrest. This samesystem can also be used to measure the height of the occupant from theseat and thus, for no additional cost assuming the rear impact occupantprotection system described in the '320 patent is provided, the firstmeasure of the occupant's morphology can be achieved. For someapplications, this may be sufficient since it is unlikely that twooperators will use the vehicle who have the same height. For otherimplementations, one or more additional measurements are used.

Referring now to FIG. 8, an automatic adjustment system for adjusting aseat (which is being used only as an example of a vehicle component) isshown generally at 100 with a movable headrest 111 and ultrasonic sensor120 and ultrasonic receiver 121 for measuring the height of the occupantof the seat. Power means such as motors 191, 192, and 193 connected tothe seat for moving the base of the seat, control means such as acontrol circuit, system or module 150 connected to the motors and aheadrest actuation mechanism using servomotors 160 and 170, which may beservomotors, are also illustrated. The seat 110 and headrest 111 areshown in phantom. Vertical motion of the headrest 111 is accomplishedwhen a signal is sent from control module 150 to servomotor 160 througha wire 131. Servomotor 160 rotates lead screw 162 which engages with athreaded hole in member 164 causing it to move up or down depending onthe direction of rotation of the lead screw 162. Headrest support rods165 and 166 are attached to member 164 and cause the headrest 111 totranslate up or down with member 164. In this manner, the verticalposition of the headrest can be controlled as depicted by arrow A—A.Ultrasonic transmitter and receiver 120,121 may be replaced by otherappropriate wave-generating and receiving devices, such aselectromagnetic, active infrared transmitters and receivers.

Wire 132 leads from control module 150 to servomotor 170 which rotateslead screw 172. Lead screw 172 engages with a threaded hole in shaft 173which is attached to supporting structures within the seat shown inphantom. The rotation of lead screw 172 rotates servo motor support 161,upon which servomotor 160 is situated, which in turn rotates headrestsupport rods 165 and 166 in slots 168 and 169 in the seat 110. Rotationof the servomotor support 161 is facilitated by a rod 171 upon which theservo motor support 161 is positioned. In this manner, the headrest 111is caused to move in the fore and aft direction as depicted by arrowB—B. Naturally there are other designs which accomplish the same effectin moving the headrest up and down and fore and aft.

The operation of the system is as follows. When an adult or childoccupant is seated on a seat containing the headrest and control systemdescribed above as determined by the neural network circuit 25, theultrasonic transmitter 120 emits ultrasonic energy which reflects off ofthe head of the occupant and is received by receiver 121. An electroniccircuit in control module 150 contains a microprocessor which determinesthe distance from the head of the occupant based on the time between thetransmission and reception of an ultrasonic pulse. Control module 150may be within the same microprocessor as neural network circuit 25 orseparate therefrom. The headrest 111 moves up and down until it findsthe top of the head and then the vertical position closest to the headof the occupant and then remains at that position. Based on the timedelay between transmission and reception of an ultrasonic pulse, thesystem can also determine the longitudinal distance from the headrest tothe occupant's head. Since the head may not be located precisely in linewith the ultrasonic sensors, or the occupant may be wearing a hat, coatwith a high collar, or may have a large hairdo, there may be some errorin this longitudinal measurement.

When an occupant sits on seat 110, the headrest 111 moves to find thetop of the occupant's head as discussed above. This is accomplishedusing an algorithm and a microprocessor which is part of control circuit150. The headrest 111 then moves to the optimum location for rear impactprotection as described in the above referenced '320 patent. Once theheight of the occupant has been measured, another algorithm in themicroprocessor in control circuit 150 compares the occupant's measuredheight with a table representing the population as a whole and from thistable, the appropriate positions for the seat corresponding to theoccupant's height is selected. For example, if the occupant measured 33inches from the top of the seat bottom, this might correspond to a 85%human, depending on the particular seat and statistical tables of humanmeasurements.

Careful study of each particular vehicle model provides the data for thetable of the location of the seat to properly position the eyes of theoccupant within the “eye-ellipse”, the steering wheel within acomfortable reach of the occupant's hands and the pedals within acomfortable reach of the occupant's feet, based on his or her size, etc.

Once the proper position has been determined by control circuit 150,signals are sent to motors 191, 192, and 193 to move the seat to thatposition. If during some set time period after the seat has beenpositioned, the operator changes these adjustments, the new positions ofthe seat are stored in association with an occupant height class in asecond table within control circuit 150. When the occupant againoccupies the seat and his or her height has once again been determined,the control circuit will find an entry in the second table which takesprecedence over the basic, original table and the seat returns to theadjusted position. When the occupant leaves the vehicle, or even whenthe engine is shut off and the door opened, the seat can be returned toa neutral position which provides for easy entry and exit from thevehicle.

The seat 110 also contains two control switch assemblies 180 and 182 formanually controlling the position of the seat 110 and headrest 111. Theseat control switches 180 permit the occupant to adjust the position ofthe seat if he or she is dissatisfied with the position selected by thealgorithm. The headrest control switches 182 permit the occupant toadjust the position of the headrest in the event that the calculatedposition is uncomfortably close to or far from the occupant's head. Awoman with a large hairdo might find that the headrest automaticallyadjusts so as to contact her hairdo. This adjustment she might findannoying and could then position the headrest further from her head. Forthose vehicles which have a seat memory system for associating the seatposition with a particular occupant, which has been assumed above, theposition of the headrest relative to the occupant's head could also berecorded. Later, when the occupant enters the vehicle, and the seatautomatically adjusts to the recorded preference, the headrest willsimilarly automatically adjust (FIG. 17B).

The height of the occupant, although probably the best initialmorphological characteristic, may not be sufficient especially fordistinguishing one driver from another when they are approximately thesame height. A second characteristic, the occupant's weight, can also bereadily determined from sensors mounted within the seat in a variety ofways as shown in FIG. 9 which is a perspective view of the seat shown inFIG. 8 with a displacement or weight sensor 200 shown mounted onto theseat. Displacement sensor 200 is supported from supports 202 and 204. Ingeneral, displacement sensor 200, or another non-displacement sensor,measures a physical state of a component affected by the occupancy ofthe seat. An occupying item of the seat will cause a force to be exerteddownward and the magnitude of this force is representative of the weightof the occupying item. Thus, by measuring this force, information aboutthe weight of the occupying item can be obtained. A physical state maybe any force changed by the occupancy of the seat and which is reflectedin the component, e.g., strain of a component, compression of acomponent, tension of a component.

Referring now to FIG. 9A, which is a view of the apparatus of FIG. 9taken along line 9A—9A, seat 230 is constructed from a cushion or foamlayer 232 which is supported by a spring system 234 which is in contactand/or association with the displacement sensor 200. As shown,displacement sensor 200 is underneath the spring system 234 but thisrelative positioning is not a required feature of the invention. Thedisplacement sensor 200 comprises an elongate cable 205 retained at oneend by support 210 and a displacement sensor 220 situated at an oppositeend. This displacement sensor 220 can be any of a variety of suchdevices including, but not limited to, a linear rheostat, a linearvariable differential transformer (LVDT), a linear variable capacitor,or any other length measuring device. Alternately, as shown in FIG. 9C,the cable can be replaced with one or more springs 242 retained betweensupports 210 and the tension in the spring measured using a strain gage(conventional wire or foil or a SAW strain gage) or other forcemeasuring device 244 or the strain in the seat support structure can bemeasured by appropriately placing strain gages on one or more of theseat supports as described in more detail below. The strain gage orother force measuring device could be arranged in association with thespring system 234 and could measure the deflection of the bottom surfaceof the cushion or foam layer 232.

When a SAW strain gage 244 is used as part of weight sensor 200, aninterrogator 246 could be placed on the vehicle to enable wirelesscommunication and/or power transfer to the SAW strain gage 244. As such,when it is desired to obtain the force being applied by the occupyingitem on the seat, the interrogator 246 sends a radio signal to the SAWstrain gage causing it to transmit a return signal with the measuredstrain of the spring 242. Interrogator 246 is coupled to the processorused to determine the control of the vehicle component.

As shown in FIG. 9D, one or more SAW strain gages 248 could also beplaced on the bottom surface of the cushion or foam layer 232 in orderto measure the deflection of the bottom surface which is representativeof the weight of the occupying item to the seat. An interrogator 249could also be used in this embodiment.

One seat design is illustrated in FIG. 9. Similar weight measurementsystems can be designed for other seat designs. Also, some products areavailable which can approximately measure weight based on pressuremeasurements made at or near the upper seat surface 236. It should benoted that the weight measured here will not be the entire weight of theoccupant since some of the occupant's weight will be supported by his orher feet which are resting on the floor or pedals. As noted above, theweight may also be measured by the weight sensor(s) 6 and 7 describedabove in the seated-state detecting unit.

As weight is placed on the seat surface 236, it is supported by spring234 which deflects downward causing cable 205 of the sensor 200 to beginto stretch axially. Using a LVDT as an example of length measuringdevice 220, the cable 205 pulls on rod 221 tending to remove rod 221from cylinder 223 (FIG. 9B). The movement of rod 221 out of cylinder 223is resisted by a spring 222 which returns the rod 221 into the cylinder223 when the weight is removed from the seat surface 236. The amountwhich the rod 221 is removed from the cylinder 223 is measured by theamount of coupling between the windings 226 and 227 of the transformeras is well understood by those skilled in the art. LVDT's arecommercially available devices. In this matter, the deflection of theseat can be measured which is a measurement of the weight on the seat.The exact relationship between weight and LVDT output is generallydetermined experimentally for this application.

SAW strain gages could also be used to determine the downward deflectionof the spring 234 and the deflection of the cable 205.

By use of a combination of weight and height, the driver of the vehiclecan in general be positively identified among the class of drivers whooperate the vehicle. Thus, when a particular driver first uses thevehicle, the seat will be automatically adjusted to the proper position.If the driver changes that position within a prescribed time period, thenew seat position will be stored in the second table for the particulardriver's height and weight. When the driver reenters the vehicle and hisor her height and weight are again measured, the seat will go to thelocation specified in the second table if one exists. Otherwise, thelocation specified in the first table will be used.

This system provides an identification of the driver based on twomorphological characteristics which is adequate for most cases. Asadditional features of the vehicle interior identification andmonitoring system described in the above referenced patent applicationsare implemented, it will be possible to obtain additional morphologicalmeasurements of the driver which will provide even greater accuracy indriver identification. Two characteristics may not be sufficient to relyon for theft and security purposes, however, many other driverpreferences can still be added to seat position with this level ofoccupant recognition accuracy. These include the automatic selection ofa preferred radio station, vehicle temperature, steering wheel andsteering column position, etc.

One advantage of using only the height and weight is that it avoids thenecessity of the seat manufacturer from having to interact with theheadliner manufacturer, or other component suppliers, since all of themeasuring transducers are in the seat. This two characteristic system isgenerally sufficient to distinguish drivers that normally drive aparticular vehicle. This system costs little more than the memorysystems now in use and is passive, i.e., it does not require action onthe part of the occupant after his initial adjustment has been made.

Instead of measuring the height and weight of the occupant, it is alsopossible to measure a combination of any two morphologicalcharacteristics and during a training phase, derive a relationshipbetween the occupancy of the seat, e.g., adult occupant, child occupant,etc., and the data of the two morphological characteristic. Thisrelationship may be embodied within a neural network so that during use,by measuring the two morphological characteristics, the occupancy of theseat can be determined.

Naturally, there are other methods of measuring the height of the driversuch as placing the transducers at other locations in the vehicle. Somealternatives are shown in FIG. 10 which is a side plan view wherein twoheight measuring sensors 320, 321 are shown, sensor 321 being mountedinto the headliner above the occupant's head and the other sensor 320being mounted onto the A-pillar. A sensor as used herein is thecombination of two transducers (a transmitter and a receiver) or onetransducer which can both transmit and receive. The headliner is thetrim which provides the interior surface to the roof of the vehicle andthe A-pillar is the roof-supporting member which is on either side ofthe windshield and on which the front doors are hinged. Thesetransducers may already be present because of other implementations ofthe vehicle interior identification and monitoring system described inthe above referenced patent applications. In this case, the use of bothtransducers provides a more accurate determination of location of thehead of the driver. Using transducer 321 alone, the exact position ofthe head is ambiguous since the transducer measures the distance to thehead regardless of what direction the head is. By knowing the distancefrom the head to transducer 320, the ambiguity is substantially reduced.This argument is of course dependent on the use of ultrasonictransducers. Optical transducers using CCD or CMOS arrays are nowbecoming price competitive and, as pointed out in the above referencedpatent applications, will be the technology of choice for interiorvehicle monitoring. A single CCD array of 160 by 160 pixels, forexample, coupled with the appropriate pattern recognition software, canbe used to form an image of the head of an occupant and accuratelylocate the head for the purposes of this invention.

FIG. 10 also illustrates a system where the seatbelt 330 has anadjustable upper anchorage point 331 which is automatically adjusted bya motor 332 to a location optimized based on the height of the occupant.The calculations for this feature and the appropriate control circuitrycan also be located in control module 301 or elsewhere if appropriate.

Many luxury automobiles today have the ability to control the angle ofthe seat back as well as a lumbar support. These additional motions ofthe seat can also be controlled by the seat adjustment system inaccordance with the invention. FIG. 11 is a view of the seat of FIG. 8showing motors 481 and 482 for changing the tilt of the seat back andthe lumbar support. Three motors 482 are used to adjust the lumbarsupport in this implementation. The same procedure is used for theseadditional motions as described for FIG. 8 above.

An initial table is provided based on the optimum positions for varioussegments of the population. For example, for some applications the tablemay contain a setting value for each five percentile of the populationfor each of the 6 possible seat motions, fore and aft, up and down,total seat tilt, seat back angle, lumbar position, and headrest positionfor a total of 120 table entries. The second table similarly wouldcontain the personal preference modified values of the 6 positionsdesired by a particular driver.

In FIG. 8, the ultrasonic transducers 120 and 121 were described as onebeing a transmitter and the other being a receiver. For someapplications, it is desirable to use both transducers as bothtransducers and receivers. Similarly, a third combination transmitterand receiver 122 may also be utilized as shown in FIG. 11. Thisarrangement permits many of the advantages of a phased array system tobe achieved.

The angular resolution of a transducer is proportional to the ratio ofthe wavelength to the diameter of the transmitter. Once threetransmitters and receivers are used, the approximate equivalent singletransmitter and receiver is one which has a diameter approximately equalto the shortest distance between any pair of transducers. In this case,the equivalent diameter is equal to the distance between transmitter 120or 121 and 122. This provides far greater resolution and, by controllingthe phase between signals sent by the transmitters, the direction of theequivalent ultrasonic beam can be controlled. Thus, the head of thedriver can be scanned with great accuracy and a map made of theoccupant's head. Using this technology plus an appropriate patternrecognition algorithm, such as a neural network, an accurate location ofthe driver's head can be found even when the driver's head is partiallyobscured by a hat, coat, or hairdo. This also provides at least oneother identification morphological characteristic which can be used tofurther identify the occupant, namely the diameter of the driver's head.

With knowledge of the weight of an occupant, additional improvements canbe made to automobile and truck seat designs. In particular, thestiffness of the seat can be adjusted so as to provide the same level ofcomfort for light and for heavy occupants. The damping of occupantmotions, which heretofore has been largely neglected, can also bereadily adjusted as shown on FIG. 12 which is a view of the seat of FIG.8 showing one of several possible arrangements for changing thestiffness and the damping of the seat. In the seat bottom 520, there isa container 515, the conventional foam and spring design has beenreplaced by an inflated rectangular container very much like an airmattress which contains a cylindrical inner container 518 which isfilled with an open cell urethane foam. An adjustable orifice 525connects the two container 515,518 so that air can flow in a controlledmanner therebetween. The amount of opening of orifice 525 is controlledby control circuit 150. A small air compressor 555 controls the pressurein container 515 under control of the control circuit 150. A pressuretransducer 560 monitors the pressure within container 515 and inputsthis information into control circuit 150.

The operation of the system is as follows. When an occupant sits on theseat, pressure initially builds up in the seat container 515 which givesan accurate measurement of the weight of the occupant. Control circuit150, using an algorithm and a microprocessor, then determines anappropriate stiffness for the seat and adds pressure to achieve thatstiffness. The pressure equalizes between the two containers 515 and 518through the flow of air through orifice 525. Control circuit 150 alsodetermines an appropriate damping for the occupant and adjusts theorifice 525 to achieve that damping. As the vehicle travels down theroad and the road roughness causes the seat to move up and down, theinertial force on the seat by the occupant causes the air pressure torise and fall in container 518 and also, but, much less so, in container515 since the occupant sits mainly above container 518 and container 515is much larger than container 518. The major deflection in the seattakes place first in container 518 which pressurizes and transfers airto container 515 through orifice 525. The size of the orifice openingdetermines the flow rate between the two containers and therefore thedamping of the motion of the occupant. Since this opening is controlledby control circuit 150, the amount of damping can thereby also becontrolled. Thus, in this simple structure, both the stiffness anddamping can be controlled to optimize the seat for a particular driver.Naturally, if the driver does not like the settings made by controlcircuit 150, he or she can change them to provide a stiffer or softerride.

The stiffness of a seat is the change in force divided by the change indeflection. This is important for many reasons, one of which is that itcontrols the natural vibration frequency of the seat occupantcombination. It is important that this be different from the frequencyof vibrations which are transmitted to the seat from the vehicle inorder to minimize the up and down motions of the occupant. The dampingis a force which opposes the motion of the occupant and which isdependent on the velocity of relative motion between the occupant andthe seat bottom. It thus removes energy and minimizes the oscillatorymotion of the occupant. These factors are especially important in truckswhere the vibratory motions of the driver's seat, and thus the driver,have caused many serious back injuries among truck drivers.

In an automobile, there is an approximately fixed vertical distancebetween the optimum location of the occupant's eyes and the location ofthe pedals. The distant from a driver's eyes to his or her feet, on theother hand, is not the same for all people. An individual driver nowcompensates for this discrepancy by moving the seat and by changing theangle between his or hers legs and body. For both small and largedrivers, this discrepancy cannot be fully compensated for and as aresult, their eyes are not appropriately placed. A similar problemexists with the steering wheel. To help correct these problems, thepedals and steering column should be movable as illustrated in FIG. 13which is a plan view similar to that of FIG. 10 showing a driver anddriver seat with an automatically adjustable steering column and pedalsystem which is adjusted based on the morphology of the driver. In FIG.13, a motor 650 is connected to and controls the position of thesteering column and another motor 660 is connected to and controls theposition of the pedals. Both motors 650,660 are coupled to andcontrolled by control circuit 150 wherein now the basic table ofsettings includes values for both the pedals and steering columnlocations.

As various parts of the vehicle interior identification and monitoringsystem described in the above reference patent applications areimplemented, a variety of transmitting and receiving transducers will bepresent in the vehicle passenger compartment. If several of thesetransducers are ultrasonic transmitters and receivers, they can beoperated in a phased array manner, as described above for the headrest,to permit precise distance measurements and mapping of the components ofthe passenger compartment. This is illustrated in FIG. 14 which is aperspective view of the interior of the passenger compartment showing avariety of transmitters and receivers, 700-706 which can be used in aphased array system. In addition, information can be transmitted betweenthe transducers using coded signals in a ultrasonic network through thevehicle compartment airspace. If one of these sensors is an optical CCDor CMOS array, the location of the driver's eyes can be accuratelydetermined and the results sent to the seat ultrasonically. Obviously,many other possibilities exist.

The eye ellipse discussed above is illustrated at 810 in FIG. 15, whichis a view similar to FIG. 1, showing the occupant's eyes and the seatadjusted to place the eyes at a particular vertical position for properviewing through the windshield and rear view mirror. Many systems arenow under development to improve vehicle safety and driving ease. Forexample, right vision systems are being tested which project an enhancedimage of the road ahead of the vehicle onto the windshield in a“heads-up display”. The main problem with the systems now being testedis that the projected image does not precisely overlap the image as seenthrough the windshield. This parallax causes confusion in the driver andcan only be corrected if the location of the driver's eyes is accuratelyknown. One method of solving this problem is to use the passive seatadjustment system described herein to place the occupant's eyes at theoptimum location as described above. Once this has been accomplished, inaddition to solving the parallax problem, the eyes are properly locatedwith respect to the rear view mirror 820 and little if any adjustment isrequired in order for the driver to have the proper view of what isbehind the vehicle.

Several systems are in development for determining the location of anoccupant and modifying the deployment of the airbag based of his or herposition. These systems are called “smart airbags”. The passive seatcontrol system in accordance with this invention can also be used forthis purpose as illustrated in FIG. 16. This figure is a view similar toFIG. 8 showing an inflated airbag 900 and an arrangement for controllingboth the flow of gas into and out of the airbag during a crash. Thedetermination is made based on height sensors 120, 121 and 122 locatedin the headrest, a weight sensor 200 in the seat and the location of theseat which is known by control circuit 150 (See, FIGS. 8, 9 and 9A).Other smart airbags systems rely only on the position of the occupantdetermined from various position sensors using ultrasonics or opticalsensors.

The weight sensor coupled with the height sensor and the occupant'svelocity relative to the vehicle, as determined by the occupant positionsensors, provides information as to the amount of energy which theairbag will need to absorb during the impact of the occupant with theairbag. This, along with the location of the occupant relative to theairbag, is then used to determine the amount of gas which is to beinjected into the airbag during deployment and the size of the exitorifices which control the rate of energy dissipation as the occupant isinteracting with the airbag during the crash. For example, if anoccupant is particularly heavy then it is desirable to increase theamount of gas, and thus the initial pressure, in the airbag toaccommodate the larger force which will be required to arrest therelative motion of the occupant. Also, the size of the exit orificesshould be reduced, since there will be a larger pressure tending toforce the gas out of the orifices, in order to prevent the bag frombottoming out before the occupant's relative velocity is arrested.Similarly, for a small occupant the initial pressure would be reducedand the size of the exit orifices increased. If, on the other hand, theoccupant is already close to the airbag then the amount of gas injectedinto the airbag needs to be reduced.

There are many ways of varying the amount of gas injected into theairbag some of which are covered in the patent literature and include,for example, inflators where the amount of gas generated and the rate ofgeneration is controllable. For example, in a particular hybrid inflatormanufactured by the Allied Signal Corporation, two pyrotechnic chargesare available to heat the stored gas in the inflator. Either or both ofthe pyrotechnic charges can be ignited and the timing between theignitions can be controlled to significantly vary the rate of gas flowto the airbag.

The flow of gas out of the airbag is traditionally done through fixeddiameter orifices placed in the bag fabric. Some attempts have been madeto provide a measure of control through such measures as blowout patchesapplied to the exterior of the airbag. Other systems were disclosed inU.S. patent application Ser. No. 07/541,464 filed Feb. 9, 1989, nowabandoned. FIG. 16A illustrates schematically an inflator 910 generatinggas to fill airbag 900 through control valve 920. The flow of gas out ofairbag 900 is controlled by exit control valve 930. The valve 930 can beimplemented in many different ways including, for example, a motoroperated valve located adjacent the inflator and in fluid communicationwith the airbag or a digital flow control valve as discussed above. Whencontrol circuit 150 determines the size and weight of the occupant, theseat position and the relative velocity of the occupant, it thendetermines the appropriate opening for the exit valve 930, which iscoupled to the control circuit 150. A signal is then sent from controlcircuit 150 to the motor controlling this valve which provides theproper opening.

In a like manner, other parameters can also be adjusted, such as thedirection of the airbag, by properly positioning the angle and locationof the steering wheel relative to the driver. If seatbelt pretensionersare used, the amount of tension in the seatbelt or the force at whichthe seatbelt spools out, for the case of force limiters, could also beadjusted based on the occupant morphological characteristics determinedby the system of this invention.

Once the morphology of the driver and the seat position is known, manyother objects in the vehicle can be automatically adjusted to conform tothe occupant. An automatically adjustable seat armrest, a cup holder,the cellular phone, or any other objects with which the driver interactscan be now moved to accommodate the driver. This is in addition to thepersonal preference items such as the radio station, temperature, etc.discussed above.

Once the system of this invention is implemented, additional featuresbecome possible such as a seat which automatically makes slightadjustments to help alleviate fatigue or to account for a change ofposition of the driver in the seat, or a seat which automaticallychanges position slightly based on the time of day. Many people preferto sit more upright when driving at night, for example. Other similarimprovements based on knowledge of the occupant morphology will nowbecome obvious to those skilled in the art.

In the above-described component adjustment systems and methods, one ofthe characteristics of the occupying item that may be measured is theweight. Several non-limiting examples of weight measuring apparatus willnow be described which may be used in the above-described systems andmethods.

In a first embodiment of a weight measuring apparatus shown in FIG. 18,four strain gage weight sensors or transducers are used, two beingillustrated at 1010 and 1011 on one side of a bracket of the supportstructure of the seat and the other two being at the same locations onanother bracket of the support (i.e., hidden on the correspondinglocations on the other side of the support). The support structure ofthe seat supports the seat on a substrate such as a floor pan of thevehicle. Each of the strain gage transducers 1010,1011 also containselectronic signal conditioning apparatus, e.g., amplifiers, analog todigital converters, filters etc., which is associated such that outputfrom the transducers is a digital signal. This electronic signal travelsfrom transducer 1010 to transducer 1011 through a wire 1020. Similarly,wire 1021 transmits the output from transducers 1010 and 1011 to thenext transducer in the sequence (one of the hidden transducers).Additionally, wire 1022 carries the output from these three transducerstoward the fourth transducer (the other hidden transducer) and wire 1023finally carries all four digital signals to an electronic control systemor module 1030. These signals from the transducers 1010,1011 are time orfrequency division multiplexed as is well known in the art. The seatposition is controlled by motors 1040 as described in detail in U.S.Pat. No. 5,179,576, which is included herein by reference. Finally, theseat is bolted onto the support structure through bolts not shown whichattach the seat through holes 1050 in the brackets.

By placing the signal conditioning electronics, analog to digitalconverters, and other appropriate electronic circuitry adjacent thestrain gage element, the four transducers can be daisy chained orotherwise attach together and only a single wire is required to connectall of the transducers to the control module 1030 as well as provide thepower to run the transducers and their associated electronics.

The control system 1030, e.g., a microprocessor, is arranged to receivethe digital signals from the transducers 1010,1011 and determine theweight of the occupying item of the seat based thereon. In other words,the signals from the transducers 1010,1011 are processed by the controlsystem 1030 to provide an indication of the weight of the occupying itemof the seat, i.e., the force exerted by the occupying item on the seatsupport structure.

A typical manually controlled seat structure is illustrated in FIG. 19and described in greater detail in U.S. Pat. No. 4,285,545. The seat1056 (only the frame of which is shown) is attached to a pair of slidemechanisms 1058 in the rear thereof through support members such asrectangular tubular structures 1060 angled between the seat 1056 and theslide mechanisms 1058. The front of the seat 1056 is attached to thevehicle (more particularly to the floor pan) through another supportmember such as a slide member 1062, which is engaged with a housing1064. Slide mechanisms 1058, support members 1060, slide member 1062 andhousing 1064 constitute the support structure for mounting the seat on asubstrate, i.e., the floor pan. Strain gage transducers are located forthis implementation at 1065 and 1066, strain gage transducer 1065 beingmounted on each tubular structure 1060 (only one of which is shown) andstrain gage transducer 1066 being mounted on slide member 1062. When anoccupying item is situated on the seat cushion (not shown), each of thesupport members 1060 and 1062 are deformed or strained. This strain ismeasured by transducers 1065 and 1066, respectively, to enable adetermination of the weight of the item occupying the seat. Morespecifically, a control system or module or other compatible processingunit (not shown) is coupled to the strain gage transducers 1065,1066,e.g., via electrical wires (not shown), to receive the measured strainand utilize the measured strain to determine the weight of the occupyingitem of the seat. The determined weight, or the raw measured strain, maybe used to control a vehicular component such as the airbag.

Support members 1060 are substantially vertically oriented and arepreferably made of a sufficiently rigid, non-bending component.

FIG. 19A illustrates an alternate arrangement for the seat supportstructures wherein a gusset 1068 has been added to bridge the angle onthe support member 1060. Strain gage transducer 1069 is placed on thisgusset 1068. Since the gusset 1068 is not a supporting member, it can bemade considerably thinner than the seat support member 1060. As the seatis loaded by an occupying item, the seat support member 1060 will bend.Since the gusset 1068 is relatively weak, greater strain will occur inthe gusset 1068 than in the support member 1060. The existence of thisgreater strain permits more efficient use of the strain gage dynamicrange thus improving the accuracy of the weight measurement.

FIG. 19B illustrates a seat transverse support member 1070 of the seatshown in FIG. 19, which is situated directly loaded by the vehicle seatand thus will provide an average measurement of the force exerted orweight of the occupying item. The deflection or strain in support member1070 is measured by a strain gage transducer 1072 mounted on the supportmember 1070 for this purpose. In some applications, the support member1070 will occupy the entire space fore and aft below the seat cushion.Here it is shown as a relatively narrow member. The strain gagetransducer 1072 is coupled, e.g., via an electrical wire (not shown), toa control module or other processing unit (not shown) which utilizes themeasured strain to determine the weight of the occupying item of theseat.

In FIG. 19, the support members 1060 are shown as rectangular tubeshaving an end connected to the seat 1056 and an opposite end connectedto the slide mechanisms 1058. In the constructions shown in FIGS.20A-20C, the rectangular tubular structure has been replaced by acircular tube where only the lower portion of the support isillustrated. FIGS. 20A-20C show three alternate ways of improving theaccuracy of the strain gage system, i.e., the accuracy of themeasurements of strain by the strain gage transducers. Generally, areduction in the stiffness of the support member to which the straingage transducer is mounted will concentrate the force and therebyimprove the strain measurement. There are several means disclosed belowto reduce the stiffness of the support member. These means are notexclusive and other ways to reduce the stiffness of the support memberare included in the invention and the interpretation of the claims.

In each illustrated embodiment, the transducer is represented by 1065and the substantially vertically oriented support member correspondingto support member 1060 in FIG. 19 has been labeled 1060A. In FIG. 20A,the tube support member 1060A has been cut to thereby form two separatetubes having longitudinally opposed ends and an additional tube section1074 is connected, e.g., by welding, to end portions of the two tubes.In this manner, a more accurate tube section 1074 can be used to permita more accurate measurement of the strain by transducer 1065, which ismounted on tube section 1074.

In FIG. 20B, a small circumferential cut has been made in tube supportmember 1060A so that a region having a smaller circumference than aremaining portion of the tube support member 1060A is formed. This cutis used to control the diameter of the tube support member 1060A at thelocation where strain gage transducer 1065 is measuring the strain. Inother words, the strain gage transducer 1065 is placed at a portionwherein the diameter thereof is less than the diameter of remainingportions of the tube support member 1060A. The purpose of this cut is tocorrect for manufacturing variations in the diameter of the tube supportmember 1060A. The magnitude of the cut is selected so as to notsignificantly weaken the structural member but instead to control thediameter tolerance on the tube so that the strain from one vehicle toanother will be the same for a particular loading of the seat.

In FIG. 20C, a small hole 1078 is made in the tube support member 1060Aadjacent the transducer 1065 to compensate for manufacturing toleranceson the tube support member 1060A.

From this discussion, it can be seen that all three techniques have astheir primary purpose to provide increase the accuracy of the strain inthe support member corresponding to weight on the vehicle seat.Naturally, the preferred approach would be to control the manufacturingtolerances on the support structure tubing so that the variation fromvehicle to vehicle is minimized. For some applications where accuratemeasurements of weight are desired, the seat structure will be designedto optimize the ability to measure the strain in the support members andthereby to optimize the measurement of the weight of the occupying item.The inventions disclosed herein, therefore, are intended to cover theentire seat when the design of the seat is such as to be optimized forthe purpose of strain gage weight sensing and alternately for the seatstructure when it is so optimized.

Although strain measurement devices have been discussed above, pressuremeasurement systems can also be used in the seat support structure tomeasure the weight on the seat. Such a system is illustrated in FIG. 21.A general description of the operation of this apparatus is disclosed inU.S. Pat. No. 5,785,291, which is included herein by reference. In thatpatent, the vehicle seat is attached to the slide mechanism by means ofbolts 1084. Between the seat and the slide mechanism, a shock-absorbingwasher has been used for each bolt. In the present invention, thisshock-absorbing washer has been replaced by a sandwich constructionconsisting of two washers of shock absorbing material 1080 with apressure sensitive material 1082 sandwiched in between. A variety ofmaterials can be used for the pressure sensitive material 1082, whichgenerally work on either the capacitance or resistive change of thematerial as it is compressed. The wires from this material leading tothe electronic control system are not shown in this view. The pressuresensitive material is coupled to the control system, e.g., amicroprocessor, and provides the control system with an indication ofthe pressure applied by the seat on the slide mechanism which is relatedto the weight of the occupying item of the seat. Generally, material1082 is constructed with electrodes on the opposing faces such that asthe material is compressed, the spacing between the electrodes isdecreased. This spacing change thereby changes both the resistive andthe capacitance of the sandwich which can be measured and which is afunction of the compressive force on the material. Measurement of thechange in capacitance of the sandwich, i.e., two spaced apart conductivemembers, is obtained by any method known to those skilled in the art,e.g., connecting the electrodes in a circuit with a source ofalternating or direct current. The conductive members may be made of ametal. The use of such a pressure sensor is not limited to theillustrated embodiment wherein the shock absorbing material 1080 andpressure sensitive material 1082 are placed around bolt 1084. It is alsonot limited to the use or incorporation of shock absorbing material inthe implementation.

FIG. 21A shows a substitute construction for the bolt 1084 in FIG. 21and which construction is preferably arranged in connection with theseat and the adjustment slide mechanism. A bolt-like member, hereinafterreferred to as a stud 400, is threaded 402 on both ends with a portionremaining unthreaded between the ends. A SAW strain measuring deviceincluding a SAW strain gage 404 and antenna 406 is arranged on thecenter unthreaded section of the stud 400 and the stud 400 is attachedat its ends to the seat and the slide mechanism using appropriatethreaded nuts. Based on the particular geometry of the SAW device used,the stud 400 can result in as little as a 3 mm upward displacement ofthe seat compared to a normal bolt mounting system. No wires arerequired to attach the SAW device to the stud 400. The total length ofstud 400 may be as little as 1 inch. In operation, an interrogator 408transmits a radio frequency pulse at for example, 925 MHz which excitesthe antenna 406 associated with the SAW strain gage 404. After a delaycaused by the time required for the wave to travel the length of the SAWdevice, a modified wave is re-transmitted to the interrogator 408providing an indication of the strain and thus a representative value ofthe weight of an object occupying the seat. For a seat which is normallybolted to the slide mechanism with four bolts, at least four SAW strainmeasuring devices or sensors would be used. Each conventional bolt couldthus be replaced by a stud as described above. Naturally, since theindividual SAW devices are very small, multiple such devices can beplaced on the stud to provide multiple redundant measurements or topermit the stud to be arbitrarily located with at least one SAW devicealways within direct view of the interrogator antenna.

To avoid potential problems with electromagnetic interference, the stud400 may be made of a non-metallic, possibly composite, material whichwould not likely cause or contribute to any possible electromagneticwave interference. The stud 400 could also be modified for use as anantenna.

With respect to the frequency of interrogation, if the seat isunoccupied then the frequency of interrogation can be substantiallyreduced in comparison to when the seat is occupied. For an occupiedseat, information as to the identity and/or category and position of anoccupying item of the seat can be obtained through the use of multipleweight sensors. For this reason, and due to the fact that duringpre-crash event the position of an occupying item of the seat may bechanging rapidly, interrogations as frequently as once every 10milliseconds or even faster can be desirable. This would also enable adistribution of the weight being applied to the seat being obtainedwhich provides an estimation of the position of the object occupying theseat. Using pattern recognition technology, e.g., a trained neuralnetwork, sensor fusion, fuzzy logic, etc., the identification of theobject can be ascertained based on the determined weight and/ordetermined weight distribution.

Although each of the SAW devices can be interrogated and/or poweredusing wireless means, in some cases, it may be desirable to supply powerto and or obtained information from such devices using wires.

In FIG. 22, which is a view of a seat attachment structure described inU.S. Pat. No. 5,531,503, where a more conventional strain gage load celldesign designated 1100 is utilized. One such load cell design 1100 isillustrated in detail in FIG. 22A.

A cantilevered beam load cell design using a half bridge strain gagesystem 1110 is shown in FIG. 22A. Fixed resistors mounted within theelectronic package, which is not shown in this drawing, provide theremainder of the whetstone bridge system. The half bridge system isfrequently used for economic reasons and where some sacrifice inaccuracy is permissible. The load cell 110 includes a member on whichthe strain gage 1110 is situated. The strain gage 1100 includesstrain-measuring elements 1112 and 1114 arranged on the load cell. Thelongitudinal element 1112 measures the tensile strain in the beam whenit is loaded by the seat and its contents, not shown, which is attachedto end 1122 of bolt 1120. The load cell is mounted to the vehicle orother substrate using bolt 1130. Temperature compensation is achieved inthis system since the resistance change in strain elements 1112 and 1114will vary the same amount with temperature and thus the voltage acrossthe portions of the half bridge will remain the same. The strain gage1100 is coupled to a control system (e.g., a microprocessor-not shown)via wires 1124 and receives the measured tensile strain and determinesthe weight of an occupying item of the seat based thereon.

One problem with using a cantilevered load cell is that it imparts atorque to the member on which it is mounted. One preferred mountingmember on an automobile is the floor-pan which will support significantvertical loads but is poor at resisting torques since floor-pans aretypically about 1 mm (0.04 inches) thick. This problem can be overcomethrough the use of a simply supported load cell design designated 1200as shown in FIG. 22B.

In FIG. 22B, a full bridge strain gage system 1210 is used with all fourelements 1212,1214 mounted on the top of a beam 1205. Elements 1212 aremounted parallel to the beam 1205 and elements 1214 are mountedperpendicular to it. Since the maximum strain is in the middle of thebeam 1205, strain gage 1210 is mounted close to that location. The loadcell, shown generally as 1200, is supported by the floor pan, not shown,at supports 1230 that are formed by bending the beam 1205 downward atits ends. Fasteners 1220 fit through holes 1222 in the beam 1205 andserve to hold the load cell 1200 to the floor pan without puttingsignificant forces on the load cell 1200. Holes are provided in thefloor-pan for bolt 1240 and for fasteners 1220. Bolt 1240 is attached tothe load cell 1200 through hole 1250 of the beam 1205 which serves totransfer the force from the seat to the load cell 1200.

The electronics package is potted within hole 1262 using urethanepotting compound 1244 and includes signal conditioning circuits, amicroprocessor with integral ADCs 1280 and a flex circuit 1275 (FIG.22C). The flex circuit 1275 terminates at an electrical connector 1290for connection to other vehicle electronics, e.g., a control system. Thebeam 1205 is slightly tapered at location 1232 so that the strain isconstant in the strain gage.

Although thus far only beam type load cells have been described, othergeometries can also be used. One such geometry is a tubular type loadcell. Such a tubular load cell is shown generally at 1300 in FIG. 22Dand instead of an elongate beam, it includes a tube. It also comprises aplurality of strain sensing elements 1310 for measuring tensile andcompressive strains in the tube as well as other elements, not shown,which are placed perpendicular to the elements 1310 to provide fortemperature compensation. Temperature compensation is achieved in thismanner, as is well known to those skilled in the art of the use ofstrain gages in conjunction with a whetstone bridge circuit, sincetemperature changes will affect each of the strain gage elementsidentically and the total effect thus cancels out in the circuit. Thesame bolt 1340 can be used in this case for mounting the load cell tothe floor-pan and for attaching the seat to the load cell.

Another alternate load cell design shown generally in FIG. 22E as 1400makes use of a torsion bar 1410 and appropriately placed torsionalstrain sensing elements 1420. A torque is imparted to the bar 1410 bymeans of lever 1430 and bolt 1440 which attaches to the seat structurenot shown. Bolts 1450 attach the mounting blocks 1460 at ends of thetorsion bar 1410 to the vehicle floor-pan.

The load cells illustrated above are all preferably of the foil straingage type. Other types of strain gages exist which would work equallywhich include wire strain gages and strain gages made from silicon.Silicon strain gages have the advantage of having a much larger gagefactor and the disadvantage of greater temperature effects. For thehigh-volume implementation of this invention, silicon strain gages havean advantage in that the electronic circuitry (signal conditioning,ADCs, etc.) can be integrated with the strain gage for a low costpackage. Other strain gage materials and load cell designs may, ofcourse, be incorporated within the teachings of this invention.

In particular, a surface acoustical wave (SAW) strain gage can be usedin place of conventional wire, foil or silicon strain gages and thestrain measured either wirelessly or by a wire connection. For SAWstrain gages, the electronic signal conditioning can be associateddirectly with the gage or remotely in an electronic control module asdesired. For SAW strain gages, the problems discussed above with lowsignal levels requiring bridge structures and the methods fortemperature compensation may not apply. Generally, SAW strain gages aremore accurate that other technologies but may require a separate sensorto measure the temperature for temperature compensation depending on thematerial used. Materials that can be considered for SAW strain gages arequartz, lithium niobate, lead zirconate, lead titenate, zinc oxide,polyvinylidene fluoride and other piezoelectric materials.

Many seat designs have four attachment points for the seat structure toattach to the vehicle. Since the plane of attachment is determined bythree points, the potential exists for a significant uncertainty orerror to be introduced. This problem can be compounded by the method ofattachment of the seat to the vehicle. Some attachment methods usingbolts, for example, can introduce significant strain in the seatsupporting structure. Some compliance therefore must be introduced intothe seat structure to reduce these attachment induced stresses to aminimum. Too much compliance, on the other hand, can significantlyweaken the seat structure and thereby potentially cause a safety issue.This problem can be solved by rendering the compliance section of theseat structure highly nonlinear or significantly limiting the range ofthe compliance. One of the support members, for example, can be attachedto the top of the seat structure through the use of the pinned jointwherein the angular rotation of the joint is severely limited. Methodswill now be obvious to those skilled in the art to eliminate theattachment induced stress and strain in the structure which can causeinaccuracies in the strain measuring system.

In the examples illustrated above, strain measuring elements have beenshown at each of the support members. This of course is necessary if anaccurate measurement of the weight of the occupying item of the seat isto be determined. For this case, typically a single value is inputtedinto the neural network representing weight. Experiments have shown,however, for the four strain gage transducer system, that most of theweight and thus most of the strain occurs in the strain elements mountedon the rear seat support structural members. In fact, about 85 percentof the load is typically carried by the rear supports. Little accuracyis lost therefore if the forward strain measuring elements areeliminated. Similarly, for most cases, the two rear mounted supportstrain elements measure approximately the same strain. Thus, theinformation represented by the strain in one rear seat support issufficient to provide a reasonably accurate measurement of the weight ofthe occupying item of the seat.

If a system consisting of eight transducers is considered, fourultrasonic transducers and four weight transducers, and if costconsiderations require the choice of a smaller total number oftransducers, it is a question of which of the eight transducers shouldbe eliminated. Fortunately, the neural network technology provides atechnique for determining which of the eight transducers is mostimportant, which is next most important, etc. If the six most criticaltransducers are chosen, that is the six transducers which contain themost useful information as determined by the neural network, and aneural network can be trained using data from those six transducers andthe overall accuracy of the system can be determined. Experience hasdetermined, for example, that typically there is almost no loss inaccuracy by eliminating two of the eight transducers, that is two of thestrain gage weight sensors. A slight loss of accuracy occurs when one ofthe ultrasonic transducers is then eliminated.

This same technique can be used with the additional transducersdescribed above. A transducer space can be determined with perhapstwenty different transducers comprised of ultrasonic, optical,electromagnetic, motion, heartbeat, weight, seat track, seatbelt payout,seatback angle etc. transducers. The neural network can then be used inconjunction with a cost function to determine the cost of systemaccuracy. In this manner, the optimum combination of any system cost andaccuracy level can be determined.

In many situations where the four strain measuring weight sensors areapplied to the vehicle seat structure, the distribution of the weightamong the four strain gage sensors, for example, well very significantlydepending on the position of the seat in the vehicle and particularlythe fore and aft and secondarily the seatback angle position. Asignificant improvement to the accuracy of the strain gage weightsensors, particularly if less than four such sensors are used, canresult by using information from a seat track position and/or a seatbackangle sensor. In many vehicles, such sensors already exist and thereforethe incorporation of this information results in little additional costto the system and results in significant improvements in the accuracy ofthe weight sensors.

There have been attempts to use seat weight sensors to determine theload distribution of the occupying item and thereby reach a conclusionabout the state of seat occupancy. For example, if a forward facinghuman is out of position, the weight distribution on the seat will bedifferent than if the occupant is in position. Similarly a rear facingchild seat will have a different weight distribution than a forwardfacing child seat. This information is useful for determining the seatedstate of the occupying item under static or slowly changing conditions.For example, even when the vehicle is traveling on moderately roughroads, a long term averaging or filtering technique can be used todetermine the total weight and weight distribution of the occupyingitem. Thus, this information can be useful in differentiating between aforward facing and rear facing child seat.

It is much less useful however for the case of a forward facing human orforward facing child seat that becomes out of position during a crash.Panic braking prior to a crash, particularly on a rough road surface,will cause dramatic fluctuations in the output of the strain sensingelements. Filtering algorithms, which require a significant time sliceof data, will also not be particularly useful. A neural network or otherpattern recognition system, however, can be trained to recognize suchsituations and provide useful information to improve system accuracy.

Other dynamical techniques can also provide useful informationespecially if combined with data from the vehicle crash accelerometer.By studying the average weight over a few cycles, as measured by eachtransducer independently, a determination can be made that the weightdistribution is changing. Depending on the magnitude of the change adetermination can be made as to whether the occupant is being restrainedby a seatbelt. It a seatbelt restraint is not being used, the outputfrom the crash accelerometer can be used to accurately project theposition of the occupant during pre crash braking and eventually theimpact itself providing his or her initial position is known.

In this manner, a weight sensor with provides weight distributioninformation can provide useful information to improve the accuracy ofthe occupant position sensing system for dynamic out of positiondetermination. Naturally, even without the weight sensor information,the use of the vehicle crash sensor data in conjunction with any meansof determining the belted state of the occupant will dramaticallyimprove the dynamic determination of the position of a vehicle occupant.

Although several preferred embodiments are illustrated and describedabove, there are other possible combinations using different sensorswhich measure either the same or different morphologicalcharacteristics, such as knee position, of an occupant to accomplish thesame or similar goals as those described herein. There are also numerousadditional applications in addition to those described above. Thisinvention is not limited to the above embodiments and should bedetermined by the following claims.

It should be mentioned that the adjustment system may be used inconjunction with each vehicle seat. In this case, if a seat isdetermined to be unoccupied, then the processor means may be designed toadjust the seat for the benefit of other occupants, i.e., if a frontpassenger side seat is unoccupied but the rear passenger side seat isoccupied, then adjustment system might adjust the front seat for thebenefit of the rear-seated passenger, e.g., move the seat base forward.

In one weight measuring method in accordance with the inventiondisclosed above, at least one strain gage transducer is mounted at arespective location on the support structure and provides a measurementof the strain of the support structure at that location, and the weightof the occupying item of the seat is determined based on the strain ofthe support structure measured by the strain gage transducer(s). Inanother method, the seat includes the slide mechanisms for mounting theseat to a substrate and bolts for mounting the seat to the slidemechanisms, the pressure exerted on the seat is measured by at least onepressure sensor arranged between one of the slide mechanisms and theseat. Each pressure sensor typically comprises first and second layersof shock absorbing material spaced from one another and a pressuresensitive material interposed between the first and second layers ofshock absorbing material. The weight of the occupying item of the seatis determined based on the pressure measured by the at least onepressure sensor. In still another method for measuring the weight of anoccupying item of a seat, a load cell is mounted between the seat and asubstrate on which the seat is supported. The load cell includes amember and a strain gage arranged thereon to measure tensile straintherein caused by weight of an occupying item of the seat. The weight ofthe occupying item of the seat is determined based on the strain in themember measured by the strain gage. Naturally, the load cell can beincorporated at other locations in the seat support structure and neednot be between the seat and substrate. In such a case, however, the seatwould need to be especially designed for that particular mountinglocation. The seat would then become the weight measuring device.

Furthermore, although the weight measuring system and apparatusdescribed above are described for particular use in a vehicle, it is ofcourse possible to apply the same constructions to measure the weight ofan occupying item on other seats in non-vehicular applications, if aweight measurement is desired for some purpose.

Thus, disclosed above are apparatus for measuring the weight of anoccupying item of a seat including at least one strain gage transducer,each mounted at a respective location on a support structure of the seatand arranged to provide a measurement of the strain of the supportstructure thereat. A control system is coupled to the strain gagetransducer(s) for determining the weight of the occupying item of theseat based on the strain of the support structure measured by the straingage transducer(s). The support structure of the seat is mounted to asubstrate such as a floor pan of a motor vehicle. Electrical connectionmeans such as wires connect the strain gage transducer(s) to the controlsystem. Each strain gage transducer may incorporate signal conditioningcircuitry and an analog to digital converter such that the measuredstrain is output as a digital signal. The positioning of the strain gagetransducer(s) depends in large part on the actual construction of thesupport structure of the seat. Thus, when the support structurecomprises two elongate slide mechanisms adapted to be mounted on thesubstrate and support members for coupling the seat to the slidemechanisms, several strain gage transducers may be used, each arrangedon a respective support member. If the support structure furtherincludes a slide member, another strain gage transducer may be mountedthereon. Means for increasing the accuracy of the strain gagetransducers and/or concentrating the strain caused by occupancy of theseat are advantageous and include, for example, forming a support memberfrom first and second tubes having longitudinally opposed ends and athird tube overlying the opposed ends of the first and second tubes andconnected to the first and second tubes whereby a strain gage transduceris arranged on the third tube. Naturally, other structural shapes may beused in place of one or more of the tubes.

Another disclosed embodiment of an apparatus for measuring the weight ofan occupying item of a seat includes slide mechanisms for mounting theseat to a substrate and bolts for mounting the seat to the slidemechanisms, the apparatus comprises at least one pressure sensorarranged between one of the slide mechanisms and the seat for measuringpressure exerted on the seat. Each pressure sensor may comprise firstand second layers of shock absorbing material spaced from one anotherand a pressure sensitive material interposed between the first andsecond layers of shock absorbing material. A control system is coupledto the pressure sensitive material for determining the weight of theoccupying item of the seat based on the pressure measured by the atleast one pressure sensor. The pressure sensitive material may includean electrode on upper and lower faces thereof.

Another disclosed embodiment of an apparatus for measuring the weight ofan occupying item of a seat includes a load cell adapted to be mountedto the seat and to a substrate on which the seat is supported. The loadcell includes a member and a strain gage arranged thereon to measuretensile strain in the member caused by weight of an occupying item ofthe seat. A control system is coupled to the strain gage for determiningthe weight of an occupying item of the seat based on the strain in themember measured by the strain gage. If the member is a beam and thestrain gage includes two strain sensing elements, then onestrain-sensing element is arranged in a longitudinal direction of thebeam and the other is arranged in a transverse direction of the beam. Iffour strain sensing elements are present, a first pair is arranged in alongitudinal direction of the beam and a second pair is arranged in atransverse direction of the beam. The member may be a tube in whichcase, a strain-sensing element is arranged on the tube to measurecompressive strain in the tube and another strain sensing element isarranged on the tube to measure tensile strain in the tube. The membermay also be an elongate torsion bar mounted at its ends to thesubstrate. In this case, the load cell includes a lever arranged betweenthe ends of the torsion bar and connected to the seat such that a torqueis imparted to the torsion bar upon weight being exerted on the seat.The strain gage thus includes a torsional strain-sensing element.

Furthermore, disclosed herein is, a vehicle seat comprises a cushiondefining a surface adapted to support an occupying item, a spring systemarranged underneath the cushion and a sensor arranged in associationwith the spring system for generating a signal based on downwardmovement of the cushion and/or spring system caused by occupancy of theseat which is indicative of the weight of the occupying item. The springsystem may be in contact with the sensor. The sensor may be adisplacement sensor structured and arranged to measure displacement ofthe spring system caused by occupancy of the seat. In the alternative,the sensor may be designed to measure deflection of a bottom of thecushion, e.g., placed on the bottom of the cushion. Instead of adisplacement sensor, the sensor can comprise a spring retained at bothends and which is tensioned upon downward movement of the spring systemand measuring means for measuring a force in the spring indicative ofweight of the occupying item. Non-limiting constructions of themeasuring means include a strain gage for measuring strain of the springor measuring means comprise a force measuring device. The sensor canalso comprises a support, a cable retained at one end by the support anda length-measuring device arranged at an opposite end of the cable formeasuring elongation of the cable indicative of weight of the occupyingitem. In this case, the length measuring device may comprises acylinder, a rod arranged in the cylinder and connected to the oppositeend of the cable, a spring arranged in the cylinder and connected to therod to resist elongation of the cable and windings arranged in thecylinder. The amount of coupling between the windings provides anindication of the extent of elongation of the cable. A strain gage canalso be used to measure the change in length of the cable. In oneparticular embodiment, the sensor comprises one or more strain gagesstructured and arranged to measure a physical state of the spring systemor the seat. Electrical connection means such as wires connect thestrain gage(s) to the control system. Each strain gage transducer mayincorporate signal conditioning circuitry and an analog to digitalconverter such that the measured strain is output as a digital signal.Alternately, a surface acoustical wave (SAW) strain gage can be used inplace of conventional wire, foil or silicon strain gages and the strainmeasured either wirelessly or by a wire connection. For SAW straingages, the electronic signal conditioning can be associated directlywith the gage or remotely in an electronic control module as desired.

In a method for measuring weight of an occupying item on a seat cushionof a vehicle, a spring system is arranged underneath the cushion and asensor is arranged in association with the cushion for generating asignal based on downward movement of the cushion and/or spring systemcaused by the occupying item which is indicative of the weight of theoccupying item. The particular constructions of the spring system andsensor discussed above can be implemented in the method.

Another embodiment of a weight sensor system comprises a spring systemadapted to be arranged underneath the cushion and extend between thesupports and a sensor arranged in association with the spring system forgenerating a signal indicative of the weight applied to the cushionbased on downward movement of the cushion and/or spring system caused bythe weight applied to the seat. The particular constructions of thespring system and sensor discussed above can be implemented in thisembodiment.

An embodiment of a vehicle including an arrangement for controlling acomponent based on an occupying item of the vehicle comprises a cushiondefining a surface adapted to support the occupying item, a springsystem arranged underneath the cushion, a sensor arranged in associationwith the spring system for generating a signal indicative of the weightof the occupying item based on downward movement of the cushion and/orspring system caused by occupancy of the seat and a processor coupled tothe sensor for receiving the signal indicative of the weight of theoccupying item and generating a control signal for controlling thecomponent. The particular constructions of the spring system and sensordiscussed above can be implemented in this embodiment. The component maybe an airbag module or several airbag modules, or any other type ofoccupant protection or restraint device.

A method for controlling a component in a vehicle based on an occupyingitem comprises the steps of arranging a spring system arrangedunderneath a cushion on which the occupying item may rest, arranging asensor in association with the cushion for generating a signal based ondownward movement of the cushion and/or spring system caused by theoccupying item which is indicative of the weight of the occupying item,and controlling the component based on the signal indicative of theweight of the occupying item. The particular constructions of the springsystem and sensor discussed above can be implemented in this method.

Further, disclosed above is a vehicle seat structure which comprises aseat or cushion defining a surface adapted to contact an occupying item,slide mechanisms coupled to the seat for enabling movement of the seat,support members for supporting the seat on the slide mechanisms suchthat at least a portion of the weight of the occupying item passesthrough the support members. At least one of the support members has aregion with a lower stiffness than a remaining region of the supportmember. The remaining regions of the support member are not necessarilythe entire remaining portions of the support member and they may bemultiple regions with a lower stiffness than other regions. A straingage measurement system generates a signal indicative of the weight ofthe occupying item. The strain gage measurement system includes at leastone strain gage transducer arranged in a lower stiffness region of thesupport member to measure strain thereof. The support member(s) may betubular whereby the lower stiffness region has a smaller diameter than adiameter of the remaining region. If the support member is not tubular,the lower stiffness region may have a smaller circumference than acircumference of a remaining region of the support member. Each supportmember may have a first end connected to one of the slide mechanisms anda second end connected to the seat. Electrical connection means, such aswires or electromagnetic waves which transfer power wirelessly, connectthe strain gage transducer(s) to the control system. Each strain gagetransducer may incorporate signal conditioning circuitry and an analogto digital converter such that the measured strain is output as adigital signal. Alternately, a surface acoustical wave (SAW) strain gagecan be used in place of conventional wire, foil or silicon strain gagesand the strain transmitted either wirelessly or by a wire connection.For SAW strain gages, the electronic signal conditioning can beassociated directly with the gage or remotely in an electronic controlmodule as desired. The strain gage measurement system preferablyincludes at least one additional strain gage transducer arranged onanother support member and a control system coupled to the strain gagetransducers for receiving the strain measured by the strain gagetransducers and providing the signal indicative of the weight of theoccupying item.

In a method for measuring weight of an occupying item in a vehicle seatdisclosed above, support members are interposed between the seat andslide mechanisms which enable movement of the seat and such that atleast a portion of the weight of the occupying item passes through thesupport members, at least one of the support members is provided with aregion having a lower stiffness than a remaining region, at least onestrain gage transducer is arranged in the lower stiffness region of thesupport member to measure strain thereof and an indication of the weightof the occupying item is obtained based at least in part on the strainof the lower stiffness region of the support member measured by thestrain gage transducer(s). The support member(s) may be formed byproviding an elongate member and cutting around the circumference of theelongate member to thereby obtain the lower stiffness region or by othermeans.

A vehicular arrangement for controlling a component based on anoccupying item of the vehicle disclosed herein comprises a seat defininga surface adapted to contact the occupying item, slide mechanismscoupled to the seat for enabling movement of the seat, support membersfor supporting the seat on the slide mechanisms such that at least aportion of the weight of the occupying item passes through the supportmembers. At least one of the support members has a region with a lowerstiffness than a remaining region of the support member. A strain gagemeasurement system generates a signal indicative of the weight of theoccupying item, and a processor coupled to the strain gage measurementsystem receives the signal indicative of the weight of the occupyingitem and generates a control signal for controlling the component. Thestrain gage measurement system includes at least one strain gagetransducer arranged in the lower stiffness region of the support memberto measure strain thereof. The component can be any vehicular component,system or subsystem which can utilize the weight of the occupying itemof the seat for control, e.g., an airbag system.

Another method for controlling a component in a vehicle based on anoccupying item disclosed herein comprises the steps of interposingsupport members between a seat on which the occupying item may rest andslide mechanisms which enable movement of the seat and such that atleast a portion of the weight of the occupying item passes through thesupport members, providing at least one of the support members with aregion having a lower stiffness than a remaining region, arranging atleast one strain gage transducer in the lower stiffness region of thesupport member to measure strain thereof, and controlling the componentbased at least in part on the strain of the lower stiffness region ofthe support member measured by the strain gage transducer(s). If thecomponent is an airbag, the step of controlling the component can entailcontrolling the rate of deployment of the airbag, the start time ofdeployment, the inflation rate of the airbag, the rate of gas removalfrom the airbag and/or the maximum pressure in the airbag.

In another weight measuring system, one or more of the connectingmembers which connect the seat to the slide mechanisms comprises anelongate stud having first and second threaded end regions and anunthreaded intermediate region between the first and second threaded endregions, the first threaded end region engaging the seat and the secondthreaded end region engaging one of the slide mechanisms, and a straingage measurement system arranged on the unthreaded intermediate regionfor measuring strain in the connecting member at the unthreadedintermediate region which is indicative of weight being applied by anoccupying item in the seat. The strain gage measurement system maycomprises a SAW strain gage and associated circuitry and electriccomponents capable of receiving a wave and transmitting a wave modifiedby virtue of the strain in the connecting member, e.g., an antenna. Theconnecting member can be made of a non-metallic, composite material toavoid problems with the electromagnetic wave propagation. Aninterrogator may be provided for communicating wirelessly with the SAWstrain gage measurement system.

The weight measuring apparatus described above may be used in apparatusand methods for adjusting a vehicle component, although other weightmeasuring apparatus may also be used in the vehicle component adjustingsystems and methods described immediately below.

One embodiment of such an apparatus in accordance with inventionincludes a first measuring system for measuring a first morphologicalcharacteristic of the occupying item of the seat and a second measuringsystem for measuring a second morphological characteristic of theoccupying item. Morphological characteristics include the weight of theoccupying item, the height of the occupying item from the bottom portionof the seat and if the occupying item is a human, the arm length, headdiameter and leg length. The apparatus also includes processor means forreceiving the output of the first and second measuring systems and forprocessing the outputs to evaluate a seated-state based on the outputs.The measuring systems described herein, as well as any otherconventional measuring systems, may be used in the invention to measurethe morphological characteristics of the occupying item.

One preferred embodiment of an adjustment system in accordance with theinvention includes a plurality of wave-receiving sensors for receivingwaves from the seat and its contents, if any, and one or more weightsensors for detecting weight of an occupant in the seat or an absence ofweight applied onto the seat indicative of a vacant seat. The weightsensing apparatus may include strain sensors mounted on or associatedwith the seat structure such that the strain measuring elements respondto the magnitude of the weight of the occupying item. The apparatus alsoincludes processor means for receiving the output of the wave-receivingsensors and the weight sensor(s) and for processing the outputs toevaluate a seated-state based on the outputs. The processor means thenadjusts a part of the component or the component in its entirety basedat least on the evaluation of the seated-state of the seat. Thewave-receiving sensors may be ultrasonic sensors, optical sensors orelectromagnetic sensors. If the wave-receiving sensors are ultrasonic oroptical sensors, then they may also include transmitter means fortransmitting ultrasonic or optical waves toward the seat. If thecomponent is a seat, the system includes power means for moving at leastone portion of the seat relative to the passenger compartment andcontrol means connected to the power means for controlling the powermeans to move the portion(s) of the seat. In this case, the processormeans may direct the control means to affect the power means based atleast in part on the evaluation of the seated-state of the seat. Withrespect to the direction or regulation of the control means by theprocessor means, this may take the form of a regulation signal to thecontrol means that no seat adjustment is needed, e.g., if the seat isoccupied by a bag of groceries or a child seat in a rear orforward-facing position as determined by the evaluation of the outputfrom the ultrasonic or optical and weight sensors. On the other hand, ifthe processor means determines that the seat is occupied by an adult orchild for which adjustment of the seat is beneficial or desired, thenthe processor means may direct the control means to affect the powermeans accordingly. For example, if a child is detected on the seat, theprocessor means may be designed to lower the headrest. In certainembodiments, the apparatus may include one or more sensors each of whichmeasures a morphological characteristic of the occupying item of theseat, e.g., the height or weight of the occupying item, and theprocessor means are arranged to obtain the input from these sensors andadjust the component accordingly. Thus, once the processor meansevaluates the occupancy of the seat and determines that the occupancy isby an adult or child, then the processor means may additionally useeither the obtained weight measurement or conduct additionalmeasurements of morphological characteristics of the adult or childoccupant and adjust the component accordingly. The processor means maybe a single microprocessor for performing all of the functions describedabove. In the alternative, one microprocessor may be used for evaluatingthe occupancy of the seat and another for adjusting the component. Theprocessor means may comprise an evaluation circuit implemented inhardware as an electronic circuit or in software as a computer program.In certain embodiments, a correlation function or state between theoutput of the various sensors and the desired result (i.e., seatoccupancy identification and categorization) is determined, e.g., by aneural network that may be implemented in hardware as a neural computeror in software as a computer program. The correlation function or statethat is determined by employing this neural network may also becontained in a microcomputer. In this case, the microcomputer can beemployed as an evaluation circuit. The word circuit herein will be usedto mean both an electronic circuit and the functional equivalentimplemented on a microcomputer using software. In enhanced embodiments,a heart beat sensor may be provided for detecting the heart beat of theoccupant and generating an output representative thereof. The processormeans additionally receive this output and evaluate the seated-state ofthe seat based in part thereon. In addition to or instead of such aheart beat sensor, a capacitive sensor and/or a motion sensor may beprovided. The capacitive sensor detects the presence of the occupant andgenerates an output representative of the presence of the occupant. Themotion sensor detects movement of the occupant and generates an outputrepresentative thereof. These outputs are provided to the processormeans for possible use in the evaluation of the seated-state of theseat.

The portion of the apparatus which includes the ultrasonic, optical orelectromagnetic sensors, weight measuring means and processor meanswhich evaluate the occupancy of the seat based on the measured weight ofthe seat and its contents and the returned waves from the ultrasonic,optical or electromagnetic sensors may be considered to constitute aseated-state detecting unit. The seated-state detecting unit may furthercomprise a seat track position-detecting sensor. This sensor determinesthe position of the seat on the seat track in the forward and aftdirection. In this case, the evaluation circuit evaluates theseated-state, based on a correlation function obtain from outputs of theultrasonic sensors, an output of the one or more weight sensors, and anoutput of the seat track position detecting sensor. With this structure,there is the advantage that the identification between the flatconfiguration of a detected surface in a state where a passenger is notsitting in the seat and the flat configuration of a detected surfacewhich is detected when a seat is slid backwards by the amount of thethickness of a passenger, that is, of identification of whether apassenger seat is vacant or occupied by a passenger, can be reliablyperformed. Furthermore, the seated-state detecting unit may alsocomprise a reclining angle detecting sensor, and the evaluation circuitmay also evaluate the seated-state based on a correlation functionobtained from outputs of the ultrasonic, optical or electromagneticsensors, an output of the weight sensor(s), and an output of thereclining angle detecting sensor. In this case, if the tilted angleinformation of the back portion of the seat is added as evaluationinformation for the seated-state, identification can be clearlyperformed between the flat configuration of a surface detected when apassenger is in a slightly slouching state and the configuration of asurface detected when the back portion of a seat is slightly tiltedforward and similar difficult-to-discriminate cases. This embodiment mayeven be combined with the output from a seat track position-detectingsensor to further enhance the evaluation circuit. Moreover, theseated-state detecting unit may further comprise a comparison circuitfor comparing the output of the weight sensor(s) with a reference value.In this case, the evaluation circuit identifies an adult and a childbased on the reference value. Preferably, the seated-state detectingunit comprises: a plurality of ultrasonic, optical or electromagneticsensors for transmitting ultrasonic or electromagnetic waves toward aseat and receiving reflected waves from the seat; one or more weightsensors for detecting weight of a passenger in the seat; a seat trackposition detecting sensor; a reclining angle detecting sensor; and aneural network circuit to which outputs of the ultrasonic orelectromagnetic sensors and the weight sensor(s), an output of the seattrack position detecting sensor, and an output of the reclining angledetecting sensor are inputted and which evaluates several kinds ofseated-states, based on a correlation function obtained from theoutputs. The kinds of seated-states that can be evaluated andcategorized by the neural network include the following categories,among others, (i) a normally seated passenger and a forward facing childseat, (ii) an abnormally seated passenger and a rear-facing child seat,and (iii) a vacant seat. The seated-state detecting unit may furthercomprise a comparison circuit for comparing the output of the weightsensor(s) with a reference value and a gate circuit to which theevaluation signal and a comparison signal from the comparison circuitare input. This gate circuit, which may be implemented in software orhardware, outputs signals which evaluates several kinds ofseated-states. These kinds of seated-states can include a (i) normallyseated passenger, (ii) a forward facing child seat, (iii) an abnormallyseated passenger, (iv) a rear facing child seat, and (v) a vacant seat.With this arrangement, the identification between a normally seatedpassenger and a forward facing child seat, the identification between anabnormally seated passenger and a rear facing child seat, and theidentification of a vacant seat can be more reliably performed. Theoutputs of the plurality of ultrasonic or electromagnetic sensors, theoutput of the weight sensor(s), the outputs of the seat track positiondetecting sensor, and the outputs of the reclining angle detectingsensor are inputted to the neural network or other pattern recognitioncircuit, and the neural network circuit determines the correlationfunction, based on training thereof during a training phase. Thecorrelation function is then typically implemented in or incorporatedinto a microcomputer. For the purposes herein, neural network will beused to include both a single neural network, a plurality of neuralnetworks, and other similar pattern recognition circuits or algorithmsand combinations thereof including the combination of neural networksand fuzzy logic systems such as neural-fuzzy systems. To provide theinput from the ultrasonic or electromagnetic sensors to the neuralnetwork circuit, it is preferable that an initial reflected wave portionand a last reflected wave portion are removed from each of the reflectedwaves of the ultrasonic or electromagnetic sensors and then the outputdata is processed. This is a form of range gating. With thisarrangement, the portions of the reflected ultrasonic or electromagneticwave that do not contain useful information are removed from theanalysis and the presence and recognition of an object on the passengerseat can be more accurately performed. The neural network circuitdetermines the correlation function by performing a weighting process,based on output data from the plurality of ultrasonic or electromagneticsensors, output data from the weight sensor(s), output data from theseat track position detecting sensor if present, and/or on output datafrom the reclining angle detecting sensor if present. Additionally, inadvanced systems, outputs from the heartbeat and occupant motion sensorsmay be included.

In a disclosed method for determining the occupancy of a seat in apassenger compartment of a vehicle in accordance with the invention,waves such as ultrasonic or electromagnetic waves are transmitted intothe passenger compartment toward the seat, reflected waves from thepassenger compartment are received by a component which then generatesan output representative thereof, the weight applied onto the seat ismeasured and an output is generated representative thereof and then theseated-state of the seat is evaluated based on the outputs from thesensors and the weight measuring means. The evaluation the seated-stateof the seat may be accomplished by generating a function correlating theoutputs representative of the received reflected waves and the measuredweight and the seated-state of the seat, and incorporating thecorrelation function into a microcomputer. In the alternative, it ispossible to generate a function correlating the outputs representativeof the received reflected waves and the measured weight and theseated-state of the seat in a neural network circuit, and execute thefunction using the outputs representative of the received reflectedwaves and the measured weight as input into the neural network circuit.To enhance the seated-state determination, the position of a seat trackof the seat is measured and an output representative thereof isgenerated, and then the seated-state of the seat is evaluated based onthe outputs representative of the received reflected waves, the measuredweight and the measured seat track position. In addition to or insteadof measuring the seat track position, it is possible to measure thereclining angle of the seat, i.e., the angle between the seat portionand the back portion of the seat, and generate an output representativethereof, and then evaluate the seated-state of the seat based on theoutputs representative of the received reflected waves, the measuredweight and the measured reclining angle of the seat (and seat trackposition, if measured). Furthermore, the output representative of themeasured weight may be compared with a reference value, and theoccupying object of the seat identified, e.g., as an adult or a child,based on the comparison of the measured weight with the reference value.

In additional embodiments, the present invention involves themeasurement of one or more morphological characteristics of a vehicleoccupant and the use of these measurements to classify the occupant asto size and weight, and then to use this classification to position avehicle component, such as the seat, to a near optimum position for thatclass of occupant. Additional information concerning occupantpreferences can also be associated with the occupant class so that whena person belonging to that particular class occupies the vehicle, thepreferences associated with that class are implemented. Thesepreferences and associated component adjustments include the seatlocation after it has been manually adjusted away from the positionchosen initially by the system, the mirror location, temperature, radiostation, steering wheel and steering column positions, etc. Thepreferred morphological characteristics used are the occupant heightfrom the vehicle seat and weight of the occupant. The height isdetermined by sensors, usually ultrasonic or electromagnetic, located inthe headrest or another convenient location. The weight is determined byone of a variety of technologies that measure either pressure on ordisplacement of the vehicle seat or the force or strain in the seatsupporting structure.

Although several preferred embodiments are illustrated and describedabove, there are possible combinations using other geometries, sensors,materials and different dimensions for the components that perform thesame functions. This invention is not limited to the above embodimentsand should be determined by the following claims. For example, theweight measuring apparatus and methods described above could be used inconjunction with a seat position sensor to provide for an accuratedetermination of the identification and location of the occupying itemof the seat.

What is claimed is:
 1. A vehicle seat structure, comprising: a seatdefining a surface adapted to contact an occupying item; and a weightsensor arrangement arranged in connection with said seat for providingan indication of the weight applied by the occupying item to the surfaceof said seat, said weight sensor arrangement including conductivemembers spaced apart from one another such that a capacitance developsbetween opposed ones of said conductive members upon incorporation ofsaid conductive members in an electrical circuit, the capacitance beingbased on the space between said conductive members which varies inrelation to the weight applied by the occupying item to the surface ofsaid seat, said weight sensor arrangement further including a pair ofnon-metallic substrates and a layer of a compressible material situatedbetween said non-metallic substrates.
 2. The seat structure of claim 1,wherein said conductive members comprise a first electrode arranged on afirst side of said material layer and a second electrode arranged on asecond side of said material layer.
 3. The seat structure of claim 1,further comprising slide mechanisms adapted to support said seat on asubstrate of the vehicle while enabling movement of said seat.
 4. Theseat structure of claim 3, wherein said weight sensor arrangement isarranged in connection with said slide mechanisms.
 5. The seat structureof claim 3, wherein said weight sensor arrangement is arranged betweensaid slide mechanisms and said seat.
 6. The seat structure of claim 3,further comprising bolts for attaching said seat to said slidemechanisms.
 7. The seat structure of claim 6, wherein said conductivemembers are annular and placed on said bolts.
 8. A seat structure,comprising: a seat defining a surface adapted to contact an occupyingitem; slide mechanisms adapted to support said seat on a substrate ofthe vehicle while enabling movement of said seat; and a weight sensorarrangement interposed between said seat and said slide mechanisms formeasuring displacement of said seat which provides an indication of theweight applied by the occupying item to said seat.
 9. The seat structureof claim 8, wherein said weight sensor arrangement includes acapacitance sensor which measures a capacitance which varies in relationto the displacement of said seat.
 10. The seat structure of claim 9,wherein said capacitance sensor includes conductive members spaced apartfrom one another such that a capacitance develops between opposed onesof said conductive members upon incorporation of said conductive membersin an electrical circuit, the capacitance being based on the spacebetween said conductive members which varies in relation to the weightapplied by the occupying item to said seat.
 11. The seat structure ofclaim 10, wherein said weight sensor arrangement includes a pair ofwashers and a layer of material situated between said washers.
 12. Theseat structure of claim 11, wherein said conductive members comprise afirst electrode arranged on a first side of said material layer and asecond electrode arranged on a second side of said material layer. 13.The seat structure of claim 11, wherein said material layer is made of acompressible material.
 14. The seat structure of claim 10, furthercomprising bolts for attaching said seat to said slide mechanisms. 15.The seat structure of claim 14, wherein said conductive members areannular and placed on said bolts.
 16. The seat structure of claim 8,further comprising a bottom cushion, said weight sensor arrangementcomprising a spring system arranged underneath said cushion and a sensorarranged in association with said spring system for generating a signalbased on downward movement of said cushion caused by occupancy of theseat which is indicative of the weight of the occupying item.
 17. Theseat structure of claim 16, wherein said sensor is a displacement sensorstructured and arranged to measure displacement of said spring systemcaused by occupancy of the seat.
 18. The seat structure of claim 16,wherein said sensor comprises: a spring having first and second ends andbeing retained at said first and second ends, said spring beingtensioned upon downward movement of said spring system; and measuringmeans for measuring a force in said spring indicative of weight of theoccupying item.
 19. The seat structure of claim 18, wherein saidmeasuring means comprise a strain gage for measuring strain of saidspring.
 20. The seat structure of claim 18, wherein said measuring meanscomprise a force-measuring device.
 21. The seat structure of claim 16,wherein said sensor comprises a support, a cable retained at one end bysaid support and a length measuring device arranged at an opposite endof said cable for measuring elongation of said cable indicative ofweight of the occupying item.
 22. The seat structure of claim 16,wherein said sensor comprises at least one SAW strain gage.
 23. The seatstructure of claim 16, wherein said sensor is structured and arranged tomeasure a physical state of said spring system.
 24. The seat structureof claim 8, wherein said weight sensor arrangement comprises a linearrheostat.
 25. The seat structure of claim 8, wherein said weight sensorarrangement comprises a linear variable differential transformer. 26.The seat structure of claim 8, wherein said weight sensor arrangementcomprises a linear variable capacitor.
 27. The seat structure of claim21, wherein said length measuring device is selected from a groupconsisting of a linear rheostat, a linear variable different transformerand a linear variable capacitor.
 28. A vehicle seat structure,comprising: a seat defining a surface adapted to contact an occupyingitem; a weight sensor arrangement arranged in connection with said seatfor providing an indication of the weight applied by the occupying itemto the surface of said seat, said weight sensor arrangement includingconductive members spaced apart from one another such that a capacitancedevelops between opposed ones of said conductive members uponincorporation of said conductive members in an electrical circuit, thecapacitance being based on the space between said conductive memberswhich varies in relation to the weight applied by the occupying item tothe surface of said seat; slide mechanisms adapted to support said seaton a substrate of the vehicle while enabling movement of said seat; andbolts for attaching said seat to said slide mechanisms, said conductivemembers being annular and placed on said bolts.
 29. A vehicle seatstructure, comprising: a seat defining a surface adapted to contact anoccupying item, slide mechanisms adapted to support said seat on asubstrate of the vehicle while enabling movement of said seat; at leastone elongate stud having a first end portion attached to said seat and asecond end portion attached to one of said slide mechanisms; a straingage arranged on each of said at least one stud between said first andsecond end portions for measuring strain in said stud caused by weightapplied by the occupying item to the surface of said seat; andtransmitting means coupled to said strain gage for transmitting themeasured strain in said stud, said transmitting means comprising anantenna.
 30. The seat structure of claim 29, wherein said first andsecond end portions are threaded and said strain gage is arranged on anunthreaded portion of said stud between said first and second threadedend portions.
 31. The seat structure of claim 29, wherein said straingage is a SAW strain gage.
 32. The seat structure of claim 29, whereinsaid at least one stud comprises four studs, two of said studs beingattached to each of said slide mechanisms.
 33. The seat structure ofclaim 29, wherein said stud is made of a non-metallic material.
 34. Avehicle seat structure, comprising: a seat defining a surface adapted tocontact an occupying item; slide mechanisms adapted to support said seaton a substrate of the vehicle while enabling movement of said seat; atleast one elongate stud having a first end portion attached to said seatand a second end portion attached to one of said slide mechanisms; a SAWstrain gage arranged on each of said at least one stud between saidfirst and second end portions for measuring strain in said stud causedby weight applied by the occupying item to the surface of said seat; andtransmitting means coupled to said SAW strain gage for transmitting themeasured strain in said stud.
 35. A vehicle seat structure, comprising:a seat defining a surface adapted to contact an occupying item, slidemechanisms adapted to support said seat on a substrate of the vehiclewhile enabling movement of said seat; at least one elongate stud havinga first end portion attached to said seat and a second end portionattached to one of said slide mechanisms, said stud being made of anon-metallic material; a strain gage arranged on each of said at leastone stud between said first and second end portions for measuring strainin said stud caused by weight applied by the occupying item to thesurface of said seat, and transmitting means coupled to said strain gagefor transmitting the measured strain in said stud.